Scientists have achieved a significant milestone in the quest for universal donor blood, using enzymes from gut bacteria to create a version of blood that could potentially be transfused across different blood types. This breakthrough, detailed in a study published in Nature Microbiology on April 29, addresses the issue of compatibility between blood types, potentially mitigating shortages of type O blood, which is often in high demand due to its universal compatibility.

The process involves identifying and removing long sugar chains present in type A and B blood, which contribute to incompatibility with type O recipients. By leveraging a mixture of gut bacteria enzymes, researchers were able to strip these sugar extensions from red blood cells (RBCs), essentially making them compatible with type O blood.

Dr. Martin Olsson of Lund University in Sweden described the elegant approach of borrowing enzymes from bacteria that naturally metabolize gut mucus, as these enzymes can effectively remove the unwanted sugar chains from RBCs. This method essentially transforms type A and B blood to molecularly resemble type O blood, which lacks the antigens responsible for compatibility issues.

While previous attempts focused on removing known antigens, this study revealed that even after stripping the RBCs clean, long sugar chains remained, contributing to incompatibility. By utilizing enzymes from Akkermansia muciniphila, a gut bacteria species, researchers demonstrated a significant increase in compatibility between type A or B blood and type O plasma after removing both the antigens and extensions.

However, challenges remain, particularly with type A blood, which appears to be more complex biochemically. Only a fraction of type A donor plasma initially showed compatibility, highlighting the need for further refinement of the enzyme cocktail to improve efficacy.

Despite these hurdles, this study marks a promising step toward developing universal donor blood. Dr. Steven Spitalnik of Columbia University emphasized the need to ensure the safety and viability of treated red cells in circulation before clinical implementation. While more research is necessary, this breakthrough brings us closer to overcoming the limitations of blood compatibility, potentially revolutionizing transfusion medicine.