Enzyme treatment could make donor organs compatible with any patient
Matching blood types from donor to recipient is one of the major problems in organ donation. Now, a team of researchers in Canada has developed an enzyme treatment to convert donated organs to the universal O blood type, allowing them to be safely transplanted into any patient.
A person’s blood type is determined by the antigens on the surface of their red blood cells. Those with type A blood have the A antigen, type B has the B antigen, AB has both and O has neither. For blood transfusions or organ transplants, these types need to be matched to prevent dangerous immune responses like organ rejection, but that’s a messy process that sees many patients missing out.
Much research has gone into preventing organ rejection in recent years. Scientists have been experimenting with special coatings for blood vessels, drugs that increase protective T cells in organs, nanoparticles that “hide” the organ from the immune system, and protein baths that strip out all the donor’s cells so they can be replaced with the recipient’s.
For the new study, researchers from a range of institutions across Canada tested an experimental enzyme treatment to remove antigens from donated organs, essentially converting them into the universal type O. Two enzymes from the human gut, known as FpGalNAc deacetylase and FpGalactosaminidase, have previously been shown to convert type A blood cells to type O, so the team tested if they would also work for organs.
They did so using the Ex Vivo Lung Perfusion (EVLP) system, which is already used to improve organs for transplant by warming them up and pumping nutrients through them. In this case, that included these particular enzymes.
The team experimented on human lungs from type A donors (which had already been deemed unsuitable for transplant, so they weren’t taking them away from potential recipients). Pairs of lungs were run through the EVLP system – one receiving the antigen-clearing enzymes and one going without. Then both lungs were tested with blood containing high levels of anti-A antibodies, simulating an incompatible transplant.
Sure enough, the enzyme treatment successfully removed over 97 percent of the A antigens in the organs. That resulted in the treated lungs faring much better when exposed to the blood, minimizing immune injury while the control lungs showed signs of rejection.
The researchers say that this could be a major step towards making universal organs that can be transplanted into anybody who needs them.
"With the current matching system, wait times can be considerably longer for patients who need a transplant depending on their blood type," said Dr. Marcelo Cypel, senior author of the study. "Having universal organs means we could eliminate the blood-matching barrier and prioritize patients by medical urgency, saving more lives and wasting less organs.”
The research was published in the journal Science Translational Medicine.
Source: University Health Network