Scientists in British Columbia say they have created an enzyme that could one day transform any human blood into a type that could safely be transfused into any patient.

All blood is made of the same basic elements, but there are eight different blood cell types that are distinguished by the presence or absence of certain antigens, called A and B, on the surface of the cells.

These antigens can trigger an immune response that can cause a patient's immune system to attack incompatible transfused blood. Only O negative type blood, which has neither A nor B antigens, is universal and can be transfused into anyone, while O positive blood can be donated to those with four other blood types.

But now, researchers from the Centre for Blood Research at the University of British Columbia say they are close to creating a way to change all blood into universal blood, using an enzyme that simply snips off a blood cell's antigen, making it more like Type O.

“We produced a mutant enzyme that is very efficient at cutting off the sugars in A and B blood, and is much more proficient at removing the subtypes of the A-antigen that the parent enzyme struggles with,” David Kwan, a postdoctoral fellow in UBC's Department of Chemistry, said in a statement.

To create the enzyme, researchers used something called directed evolution to insert gene mutations into the enzyme until it become more effective at cutting blood cell antigens. In just five generations, the enzyme became 170 times more effective at removing A and B antigens.

The researchers say their work isn't ready to be used in a clinical setting yet because they haven't been able to perfect the enzyme to remove all of a blood cell's antigens. That's critical since the immune system is highly sensitive to even small amounts of residual antigens.

Steve Withers, a chemistry professor at UBC, says this isn’t the first time that researchers have produced blood with fewer antigens, but he believes this method has worked better than any other.

"…Until now, we needed so much of the enzyme to make it work that it was impractical,” he said in a statement. “Now I’m confident that we can take this a whole lot further.”

The researchers have published the results of their research so far in the Journal of the American Chemical Society.

Their research is supported by Canadian Blood Services and the Canadian Institutes of Health Research.