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Blood banks need a constant supply of donors to maintain their supply, but some enzymes that are already in our bodies might be able to help!

Hosted by: Stefan Chin

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It’s nearing the end of summer in the Northern Hemisphere, which means two things. One, some students are milking the last few weeks of their summer vacation for all they’re worth.

And two, because many schools aren’t in session, blood banks aren’t getting as many regular donors. In fact, the American Red Cross received 56,000 fewer donations in May and June than they needed. That’s led to a critical blood shortage.

In some places, there’s less than a day’s worth on hand for emergencies and for people that need regular transfusions. Group O blood is especially useful. It’s the most common group, and the only kind that can be given to people with other blood groups without setting off an immune response.

And soon, we might have a way to boost the stocks, and revolutionize the way we collect and manage donated blood. Scientists from the University of British Columbia have discovered enzymes from gut bacteria that seem to safely turn any blood into O blood. Your blood group is determined by the presence or absence of small chains of sugar molecules, called A and B, on the surface of your red blood cells.

Cells can have As, Bs, both As and Bs, or neither if you belong to the O group. And your immune system uses these sugar molecules as antigens to distinguish your cells from invaders. For instance, if you have A blood and you’re given a transfusion with B blood, your body flags the foreign sugars and attacks those cells.

Which would obviously be very bad. Since O blood lacks these sugars, it doesn’t trigger an immune response in anyone. That’s why it’s always in high demand and short supply in hospitals.

But if you could strip away the sugar markers from someone’s red blood cells, you could theoretically make O blood from any donation. And that’s the focus of new research presented at a meeting of the American Chemical Society earlier this week. The researchers set out looking for enzymes in gut bacteria that can cut the A and B sugar molecules off of blood cells.

Those microbes eat by chopping similar sugars off cells that line your gut. The team used an approach called metagenomics, where they sequenced the genes from lots of bacteria at once. That way, they didn’t have to try and grow thousands of different species, some of which are difficult or impossible to grow in the lab, to look for enzymes.

Instead, they took all the genes they sequenced and inserted a few of them at a time into. E. coli bacteria, which are easy to mass produce. Then, they tested all those E. coli to look for the right kind of sugar-slicing enzymes, ones that cleave away the specific sugars on the ends of the A and B antigens.

And they found some new ones! This isn’t the first time scientists have looked for enzymes that can convert blood groups. The idea was first proposed back in the 1980s.

The first of these enzymes was discovered in green coffee beans, but it only worked on B blood, and it took a lot of enzyme to do the job. So researchers have been looking for more efficient enzymes. They’ve found some better B-cutters in other bacteria, but it’s been hard to pin down a good one that cleaves A sugars.

Using less enzyme keeps the Group O blood production costs more reasonable, and it means that there’s less enzyme to remove after the blood cells are treated. Which is nice, because injecting sugar-slicing bacterial enzymes into people isn’t really any better than injecting the wrong blood. These new enzymes can cleave off A sugars, and they’re reportedly 30 times more efficient than any discovered before.

And the researchers are hoping to make them even more efficient through directed evolution, a lab process which mimics natural selection to guide changes to proteins. They can be used in whole blood, too, so the process could be as simple as adding in a special enzyme mix right when the blood is collected. This research still needs to undergo peer review, but if the enzymes really work this well, then they could completely change how blood donations are handled.

Part of the reason there’s pretty much never enough blood lying around is that donated red blood cells only survive about a month and a half max, if they’re kept cool. Your body normally filters out dying red blood cells and replaces them with fresh ones, but there isn’t an easy way to remove unhealthy cells from donated blood. So blood banks need a constant supply from donors, and it’d be a huge help for emergency situations if A, B or AB blood could be repurposed for anyone.

Finding enzymes that can efficiently convert blood is only the first step, though. As with any medical discovery, there’s a lot to be done before blood banks and hospitals can use these enzymes. Other animals don’t have the same ABO blood system that we do, so you can’t really test this stuff in them like you might a new drug.

And that means that there needs to be a battery of other safety tests before clinical trials on humans could even be considered. Previous enzymes for converting B blood to O blood have made it to clinical trials, though, so it’s definitely possible that these new ones will, too. But in the meantime, blood donations are still sorely needed.

If you want to learn more about how you might be able to help though, you can check out some links in the description. Thanks for watching this episode of SciShow News! If you want to stay up to date on the latest, greatest science news, tune in every Friday for our weekly news episode, or just click that subscribe button. [♩OUTRO].