Researchers at the University of British Columbia have discovered a way to turn Type A blood into the more in-demand Type O, in what could be a huge advance for blood donation if the technique is proven safe.
With the ability to switch types, hospitals could greatly expand the number of people they could donate a given unit of blood to.
There are four main blood types: A, B, AB and O.
Type A and B blood have specific antigens which mean it can only be donated to other people with those same antigens. Type AB blood has both antigens. So Type A blood can only be given to people with either Type A or Type AB blood, for example. If the wrong blood is given, the recipient’s immune system will attack the new blood cells.
But Type O, which lacks these antigens, can be given to anyone – which makes it incredibly sought-after in the world of blood donation.
“This could be a game changer,” said Dr. Dana Devine, chief scientist at Canadian Blood Services.
The UBC researchers’ process treats blood with enzymes from the human gut, to strip away the sugars that make up the Type A antigens, effectively turning it into Type O. The technique can also be combined with enzymes that remove the Type B antigens, meaning that any blood type could be turned into O blood.
This doesn’t change the Rh antigen, the “positive” or “negative” part associated with blood type, so it doesn’t create the truly “universal donor” blood: Type O-negative. But, it’s still a major step forward.
Hunting in the gut
Finding the right enzyme to change blood types took some sleuthing.
“The gut wall is decorated with specific sugar structures, including that of the A-antigen,” wrote lead researcher Stephen Withers, a professor of chemistry at UBC in an email. “It seemed likely that gut bacteria would have developed enzymes to opportunistically cleave these sugars as a food source.”
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They found the enzyme by screening a huge collection of more than 20,000 samples of gut bacteria to find just the right one, he said.
Expanding the blood supply
Withers, who presented his research at the annual meeting of the American Chemical Society on Tuesday, is excited by the possibilities. During times of blood shortages, like right now, with Canadian Blood Services calling for 20,000 donors before the Labour Day weekend, it would be useful to have as much Type O blood available as possible, he said.
“Our approach, if proven safe, would allow the supply of O to be expanded.”
Canadian Blood Services is also pretty excited about what this could mean. Although Type O-positive blood is the most common blood type, the blood supply is often running low on O, simply because it gets used faster, said Devine.
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“This imbalance arises because group-O blood can be transfused to any recipient and is used to treat patients in emergency settings when there is no time to determine the patient’s actual blood type.”
It wouldn’t be necessary to turn all blood donations into O blood, but it would be very useful when supplies run low or when preparing for emergency situations, she said.
This isn’t the first time that scientists have found a way to remove antigens from blood, but the UBC researchers are hoping that these enzymes are powerful enough to treat blood on a large scale, meaning it would be economically feasible to do.
Previous attempts were too expensive on a per-unit basis to actually use, said Devine, but she hopes that this new method would make it affordable.
Withers warns that he is still about two years away from testing his treated blood in people. “We have shown we can convert A blood to O using the standard tests of the Canadian Blood Services,” he said.
“However, there are a lot more tests to be done now to make sure that the enzyme did not inadvertently cause any other problems.”
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