Blood type is one of the sources of incompatibility between a donor and a recipient during a transplant. Canadian doctors have developed a rapid method to change the blood type of a graft within hours, making it compatible with more patients.
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At Toronto General Hospital Research Institute, in Canada, researchers have succeeded in changing the blood type of an organ to be transplanted. In just four hours, the lungs have changed their identity from blood type A to O. This is an important step in the creation of a universal graft, compatible with all patients.
Enzyme treatment ex-vivo can eliminate the blood group antigen in the donor’s lungs and thus make the graft universal. © University of British Columbia (Canada)
A graft compatible with all patients thanks to enzymes
Before transplanting an organ, doctors must ensure that it is compatible with the recipient to avoid rejection of the graft. The donor’s blood type must be compatible with that of the recipient – in addition to typing HLA. For patients with a rare blood group, such as B- or AB+, the wait can be very long, to the detriment of their state of health. To counter this problem, Canadian researchers have developed a technique to get rid of blood group A antigens expressed by Red cells present on a lung transplant.
The operation takes place ex-vivooutside the organism, under a dome of plastic. The graft is perfused with a cocktail of two enzymes : FpGalNAc deacetylase and FpGalactosaminidase. ” This group of enzymes that we found in the human intestine can cut sugars A and B antigens on red blood cells, converting them into universal type O cells », explains Stephen Withersa member of the research team affiliated with the University of British Columbia in Vancouver.
The objective of these preliminary tests is to ensure that the enzyme cocktail does indeed eliminate the A antigens on the red blood cells and that they do not damage the graft. The enzymes, concentrated only at 1 μg/ml, made it possible to eliminate 99% and 90% of the A antigens from the red blood cells and the aorta, respectively. A total of eight lungs underwent the same treatment, providing promising results: on average 97% of A antigens eliminated after four hours of treatment, with no observable toxicity.
Without antigen surface, the graft appears as blood group O, and becomes virtually universal, compatible with all blood groups. No human has yet been transplanted with an organ treated with this protocol, there are therefore many unknowns about the viability of the organ and the reaction of the organism. But the researchers simulated a transplant between normally incompatible people. Infusion of type O blood into the formerly type A lung – but now made universal – did not cause any adverse reactions.
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