Blood transfusions are often lifesaving when patients desperately need to replace blood lost due to surgery or injury. The problem is that blood is in low supply worldwide. To make matters worse, there are multiple blood groups, some of which are incompatible. For instance, if your blood type is O negative, you can only receive O-negative-type blood.

O negative is the universal donor type, compatible with any blood type since it lacks certain antigens on the surface of its blood cells. However, only 8% of people have O-negative blood. Furthermore, in addition to the major blood types, there are hundreds of antigens for red blood cells, some of which are unique to racial and ethnic groups.

Last year, the American Red Cross, which collects and handles distribution for about 40% of the nation’s blood donations, announced that it’s facing severe blood shortages. Many surgeries had to be canceled as hospitals and doctors were not confident they had enough blood to safely operate.

Donating blood is not merely charity — it’s a life-saving, selfless act that most of us can do from time to time. But the reality is that there aren’t that many donors. However, new research is providing an unexpected silver living.

Making blood universal

Researchers at the Technical University of Denmark (DTU) and Lund University in Sweden have discovered an amazing method to convert Type A and B blood into universal donor blood. The technique involves powerful enzymes that strip red blood cells of antigens and sugars responsible for blood type distinctions.

These enzymes, derived from human gut bacteria, effectively remove not only the common A and B antigens but also previously unrecognized variants that pose risks during transfusions. These findings hint at a near future where blood from group B donors could be universally compatible. Further work is needed, though, to treat the more complex group A blood.

“Our focus is now to investigate in detail if there are additional obstacles and how we can improve our enzymes to reach the ultimate goal of universal blood production,” says lead author Professor Maher Abou Hachem from DTU, one of the senior scientists behind the discovery.

Addressing a critical need with enzymes from the gut

The demand for donor blood remains high, driven by an aging population and the increasing prevalence of medical procedures that require blood transfusions. Managing and storing different blood types separately requires extensive logistics, escalating costs and complicating medical procedures.

The enzyme treatment developed by the research teams promises to simplify these processes significantly. By converting type-specific blood into a universal donor type, hospitals can streamline their blood supply chains, reduce waste from unused blood, and avoid the severe risks associated with mismatched blood transfusions.

At the most basic level, there are four main categories of human blood: A, B, AB, and O. This classification is based on antigens found on red blood cells and antibodies present in the plasma. Type A blood has A antigens on the red cells and anti-B antibodies in the plasma. Type B blood has B antigens with anti-A antibodies in the plasma.

You can never transfuse incompatible blood types — doing so could result in a disaster. For example, suppose a patient with Type B blood receives Type A blood. In that case, the anti-A antibodies present in the recipient’s plasma will attack the A antigens on the donor blood cells, leading to potentially fatal complications.

A new technique for an old idea

The idea of removing antigens using enzymes is not new. In fact, researchers have been removing A and B antigens for decades. However, previous attempts were not able to avoid all immune reactions related to the converted blood. This is why you don’t see this kind of blood used in clinical practice. These methods also used enzymes that are far less efficient than the ones used in this technique.

“Universal blood will create a more efficient utilization of donor blood, and also avoid giving ABO-mismatched transfusions by mistake, which can otherwise lead to potentially fatal consequences in the recipient. When we can create ABO-universal donor blood, we will simplify the logistics of transporting and administering safe blood products, while at the same time minimizing blood waste” says Professor Martin L. Olsson from Lund University.

The new technique developed by the researchers in Scandinavia hinges on enzymes from the human gut bacterium Akkermansia muciniphila. These bacteria feed on the mucus that lines the inside of the gut. The researchers learned that the complex sugars at the surface of the intestinal mucosa are very chemically similar to the antigens. For their study, the researchers tested 24 enzymes, which were used to process hundreds of blood samples.

With a patent application filed for the novel enzymes and their method of use, the team is planning a joint project to refine their approach, looking ahead to controlled patient trials and, eventually, clinical application.

“This study demonstrates the potential utility of mucin-degrading gut bacteria as valuable sources of enzymes for production of universal blood for transfusions,” the researchers concluded in their study.

The findings were reported in the journal Nature Microbiology.