The Gut Microbiome's Potential to Solve Blood Bank Shortages

Saturday - May 4 2024, 09:54 UTC - 6 months ago

Blood banks often face shortages of the universal donor type O blood. A team from Denmark and Sweden has discovered a cocktail of enzymes in gut bacteria that can efficiently convert type A and B blood into type O. This could help alleviate blood bank shortages, especially during emergencies.

Blood transfusions save lives. In the US alone, people receive around 10 million units each year. But blood banks are always short in supply—especially when it comes to the "universal donor" type O. Surprisingly, the gut microbiome may hold a solution for boosting universal blood supplies by chemically converting other blood types into the universal O. Infusing the wrong blood type—say, type A to type B—triggers deadly immune reactions. Type O blood, however, is compatible with nearly everyone. It’s in especially high demand following hurricanes, earthquakes, wildfires, and other crises because doctors have to rapidly treat as many people as possible. Sometimes, blood banks have an imbalance of different blood types—for example, too much type A, not enough universal O. This week, a team from Denmark and Sweden discovered a cocktail of enzymes that readily converts type A and type B blood into the universal donor. Found in gut bacteria, the enzymes chew up an immune-stimulating sugar molecule dotted on the surfaces of type A and B blood cells, removing their tendency to spark an immune response. Compared to previous attempts, the blend of enzymes converted A and B blood types to type O blood with "remarkably high efficiencies," the authors wrote.

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Blood types can be characterized in multiple ways, but roughly speaking, the types come in four main forms: A, B, AB, and O. These types are distinguished by what kinds of sugar molecules—called antigens—cover the surfaces of red blood cells. Antigens can trigger immune rejection if mismatched. Type A blood has A antigens; type B has B antigens; type AB has both. Type O has neither. This is why type O blood can be used for most people. It doesn’t normally trigger an immune response and is highly coveted during emergencies when it’s difficult to determine a person’s blood type. One obvious way to boost type O stock is to recruit more donors, but that’s not always possible. As a workaround, scientists have tried to artificially produce type O blood using stem cell technology. While successful in the lab, it’s expensive and hard to scale up for real-world demands. An alternative is removing the A and B antigens from donated blood. First proposed in the 1980s, this approach uses enzymes to break down the immune-stimulating sugar molecules. Like licking an ice cream cone, as the antigens gradually melt away, the blood cells are stripped of their A or B identity, eventually transforming into the universal O blood type. The technology sounds high-tech, but breaking down sugars is something our bodies naturally do every day, thanks to microbes in the gut that happily digest our food. This got scientists wondering: Can we hunt down enzymes in the digestive track to convert blood types? Over a half decade ago, a team from the University of British Columbia made headlines by using bacterial enzymes found in the gut microbiome to transform type A blood to type O. Some gut bugs eat away at mucus—a slimy substance made of sugary molecules covering the gut. These mucus linings are molecularly similar to the antigens on red blood cells. So, digestive enzymes from gut bacteria had the potential to chomp on the antigens of type A or type B blood, turning them into type O.