Canadian researchers say they may have identified substances from the human gut that could turn Type A and B blood into Type O blood — a discovery that could make blood donation simpler, especially in times of emergency.

People with Type O negative blood are considered universal donors, as they can donate blood to anyone. That’s why Type O negative blood is always in high demand during emergencies, when there is often little time to test a patient’s blood type to make sure it matches a donor.

Those with the other types of blood – Type A and Type B – have antigens on their red blood cells that prevent their blood from being donated to those who don’t match.

 

There has long been interest in finding a safe and effective way of removing the A or B antigens from red blood cells, says University of British Columbia biochemistry researcher Stephen Withers.

"If you can remove those antigens, which are just simple sugars, then you can convert A or B to O blood," he explained in a statement.

He and his colleagues decided to look for enzymes that might be able to do the job using something called "metagenomics" to analyze the genes of multiple kinds of organisms.

 

They considered analyzing mosquitoes and leeches, which naturally degrade blood, but ultimately found good candidates in the enzymes of bacteria that live in the human gut and that aid in digestion.

They found an entire family of enzymes that gut bacteria use to pluck sugars off mucins, which are the proteins that line the gut wall.

They tested how well these enzymes were at removing the sugary antigens on Type A and Type B blood, and found they were 30 times more effective than previous candidates.

The team will present the results of their research so far on Tuesday morning at the American Chemical Society’s annual meeting in Boston.

 

Withers is now working with colleagues at the Centre for Blood Research at UBC to test the enzymes on a larger scale, with the aim of then moving into clinical testing.

He also wants to engineer the most efficient sugar-removing enzyme using something called "directed evolution," which is a protein engineering technique that simulates natural evolution.

 

"I am optimistic that we have a very interesting candidate to adjust donated blood to a common type," Withers said.

"Of course, it will have to go through lots of clinical trials to make sure that it doesn‘t have any adverse consequences, but it is looking very promising."