The Enzyme That Could Transform Transfusions

2015-02-04-Joni_Blecher_150x150.jpgBy Joni Blecher

Joni Blecher is a freelance writer who has spent her career covering tech and a myriad of lifestyle topics. When she's not writing, you can find her exploring the food scene in Portland, Oregon.

Blood transfusions can save lives, but not all blood is compatible. Scientists have been trying to find an efficient way to solve this problem for decades. Now, researchers at the University of British Columbia (UBC) may have come up with the solution: an enzyme that could make Type A and Type B blood resemble Type O, known as the "universal donor." 

Blood type, like hair and eye color, is genetically pre-determined. There are four blood types: A, B, AB and O, and there are positive and negative versions of each. Antigens found on the red blood cells of A, B and AB make them incompatible with each other. If the right blood type isn't on hand for a transfusion, the results can be disastrous. However, Type O lacks the antigen and, as a result, is a universal donor that can be accepted by anyone.

Finding a way to transform Type A and B into Type O blood could potentially save thousands of lives. A and B essentially have sugars on the outside of the red blood cell (the antigen), and using enzymes to help create a universal blood type isn't a new idea -- it just hasn't been feasible. In the past, the process required large amounts of enzymes to help remove the antigens.

"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," said David Kwan, the lead author of the study and a postdoctoral fellow in the Department of Chemistry at UBC.

That mutant enzyme was created using a new technology called "directed evolution," which inserts mutations into the gene and selects the best mutants to remove the antigens. After five generations of altering the enzyme, the team at UBC ended up with an enzyme that is 170 times more effective at cutting the sugar of the Type A and Type B red blood cells.

That said, the enzyme can't remove all the antigens from Type A and Type B red blood cells, so it's not ready to hit the blood banks yet. It would need to turn the blood into a perfect Type O to move on to clinical testing. As it stands, the remaining residue on the cells could trigger a life-threatening immune response during a transfusion. If and when it does work, potentially even more donated blood will be available for transfusions in the future.

"Before our enzyme can be used clinically, further improvements by directed evolution will be necessary," says Stephen Withers, a Biochemistry Professor at UBC. "Given our success so far, we are optimistic that this will work."

Interested in blood typing and learning more about which types are compatible with each other? Check out the blood typing game from the Nobel Prize organization, and you'll quickly see what can happen when someone receives an incompatible blood transfusion.

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