Organ transplants can be life-saving, but the need to match blood types means many people are left on long waiting lists while organs go to waste. Scientists at Cambridge have now demonstrated a technique that could one day make donated organs universal, by converting them to blood type O.
Blood type is dictated by the kinds of antigens it contains – labeled A or B – and if the wrong ones are detected, an immune response will be launched that can lead to complications like organ rejection. That makes blood and organs from patients with blood type O, which have neither antigen, especially valuable as they can be transplanted into anyone.
So for the new study, researchers at Cambridge tested a way to convert organs to type O, which could greatly expand the pool of organs available for transplant. The key was a bacteria-derived enzyme called GH110B, which acts like a pair of “molecular scissors” to cut out the antigens lining the organ’s blood vessels.
The team infuses this enzyme through the organs using a normothermic perfusion machine, which flushes oxygenated blood through donated organs to preserve them better. The end result is an organ that’s effectively type O, allowing it to be transplanted into any patient that needs it.
The team first tested the technique on pieces of human kidney tissue, before moving on to three full kidneys with blood type B. The process takes about six hours, and was found to reduce blood type antigens in the organs by over 90%.
The results echo previous work earlier this year, when scientists used a similar enzyme perfusion technique to clear out type A antigens from human lungs. They also went a step further and simulated an incompatible transplant by introducing blood with high levels of anti-A antibodies, and found that the organs suffered minimal immune injury.
This important step is something that the researchers on the new study have yet to do, but they say this is next on the list. If that works, it could eventually open the door to shorter waiting lists and saved lives for people needing organ transplants, particularly those from minority backgrounds. Other recent work into preventing organ rejection has investigated special coatings for blood vessels, nanoparticles that "hide" the organ from the immune system, and protein baths that "recellularize" organs.
The research is due to be published soon in the British Journal of Surgery.
