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Universal blood type5/1/2023 ![]() But she came close to scheduling her surgery a couple of times before that - only to discover the lungs she was set to receive weren't a good match for her B-positive blood. The Niagara, Ont., resident, who was diagnosed with chronic obstructive pulmonary disease (COPD) in 2016, underwent a successful double-lung transplant in November. Having the ability to transform type A to type O, Withers says, "would broaden our supply of blood and ease these shortages.Elizabeth Ostrander spent two years on an organ transplant wait list, worrying about her oxygen levels any time she left home and wondering if she'd ever get the lungs she needed. For now, the researchers are focusing on only converting type A, as it's more common than type B blood. And Withers says researchers need to make sure the microbial enzymes have not inadvertently altered anything else on the red blood cell that could produce problems. In the United States, type A blood makes up just under one-third of the supply, meaning the availability of "universal" donor blood could almost double.īut Narla says more work is needed to ensure that all the offending A antigens have been removed, a problem in previous efforts. "The findings are very promising in terms of their practical utility," Narla says. Tiny amounts added to a unit of type A blood could get rid of the offending sugars, they found. The enzymes originally come from a gut bacterium called Flavonifractor plautii, Rahfeld, Withers, and their colleagues report today in Nature Microbiology. The enzymes also worked their magic in human blood. But when they tested two of the resulting enzymes at once-adding them to substances that would glow if the sugars were removed- the sugars came right off. ![]() Chopping this DNA up and loading different pieces into copies of the commonly used lab bacterium Escherichia coli, the researchers monitored whether any of the microbes subsequently produced proteins with the ability to remove A-defining sugars.Īt first, they didn't see anything promising. So UBC postdoc Peter Rahfeld collected a human stool sample and isolated its DNA, which in theory would include genes that encode the bacterial enzymes that digest mucins. Mucins' sugars are similar to the type-defining ones on red blood cells. Some of these microbes latch onto the gut wall, where they "eat" the sugar-protein combos called mucins that line it. But they've met with limited success, as the known enzymes that can strip the red blood cell of the offending sugars aren't efficient enough to do the job economically.Īfter 4 years of trying to improve on those enzymes, a team led by Stephen Withers, a chemical biologist at the University of British Columbia (UBC) in Vancouver, Canada, decided to look for a better one among human gut bacteria. To up the supply of universal blood, scientists have tried transforming the second most common blood, type A, by removing its "A-defining" antigens. "Around the United States and the rest of the world, there is a constant shortage," says Mohandas Narla, a red blood cell physiologist at the New York Blood Center in New York City. That makes this "universal" blood especially important in emergency rooms, where nurses and doctors may not have time to determine an accident victim's blood type. But type O cells lack these antigens, making it possible to transfuse that blood type into anyone. If a person with type A receives type B blood, or vice versa, these molecules, called blood antigens, can cause the immune system to mount a deadly attack on the red blood cells. ![]() People typically have one of four blood types-A, B, AB, or O-defined by unusual sugar molecules on the surfaces of their red blood cells. "This is a first, and if these data can be replicated, it is certainly a major advance," says Harvey Klein, a blood transfusion expert at the National Institutes of Health's Clinical Center in Bethesda, Maryland, who was not involved with the work. If the process pans out, blood specialists suggest it could revolutionize blood donation and transfusion. Now, researchers analyzing bacteria in the human gut have discovered that microbes there produce two enzymes that can convert the common type A into a more universally accepted type. But recipients can't take just any blood: For a transfusion to be successful, the patient and donor blood types must be compatible. ![]() On any given day, hospitals across the United States burn through some 16,500 liters (35,000 pints) of donated blood for emergency surgeries, scheduled operations, and routine transfusions. ![]()
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