Researchers in Canada say they’ve found a way to help people who otherwise would be left languishing on the organ transplant list. In new research this week, they detail converting lungs from people with type A blood into lungs that could be donated to anyone, without heavily damaging them or causing acute rejection. Assuming the team’s work is further validated and tested to be safe, it may someday expand the pool of universal donor lungs.
Donated organs and tissues have to be carefully vetted to ensure compatibility between the donor and recipient. One of these important criteria is blood type, since the body’s immune system will quickly attack antigens in blood or organs from an incompatible type. People with type O blood can donate to anyone else, because they lack the antigens that would trigger other people’s immune systems, while people with type AB blood can receive organs from anyone else.
Unfortunately, there are only so many organs from universal donors around at any given time, and this can further worsen shortages for certain people in need of a transplant. Research has shown, for instance, that potential organ recipients with type O blood (who can only get organs from other type O donors) spend more time on the waiting list than others and are more likely to die as a result. And mismatched organs may even get thrown out, never seeing any use at all. This new research, published Wednesday in Science Translational Medicine, could one day help solve these problems.
Researchers from the University of Toronto and other Canadian universities collaborated for the study. Based on earlier research, they theorized that two enzymes combined could largely remove the antigens associated with type A blood in donated lungs, effectively converting them into type O lungs. They tested the process out first in human tissue from the aorta, the largest artery of the body, then on eight donated human lungs earlier deemed unsuitable for transplantation.
In both tests, the team’s concoction appeared to work. Within four hours of the lungs being doused in the enzymes, more than 97% of type A antigens were cleared from them, and there were no apparent signs of lung toxicity. Afterwards, the team exposed the lungs to blood plasma from type O individuals and documented minimal reaction from normally hostile antibodies, indicating that the lungs could be safely tolerated in these people. And the process, according to study author Marcelo Cypel, a professor of surgery at the University of Toronto, should work similarly well with any donated organ, not just the lungs.
The findings are based on a small sample size, so they should be taken with some caution. It will take more research, most importantly clinical trials and follow-up data of people who receive these converted organs, to truly know whether this method can be safe over the long term. But the team hopes to begin performing clinical trials within the next 12 to 18 months, and, should it pan out as hoped, their work may lead to more saved lives down the road. Nowadays, for instance, about 55% of donated organs come from type O donors, and this process could make it so that about 80% of organs fall into the universal donor category, according to the team.
“Often times we can’t transplant the sickest patient with the next donor. Some patients die on the wait list because of that. Some patients have to wait a very long time, ” Cypel said. “If we remove ABO as a barrier for match we will have moved a big step up in fairness in organ donor allocation.”