Organ Transplantation: Researchers Change Blood Type A Donor Lungs to Universal Type O Blood Lungs

Blood type is one of the sources of incompatibility between a donor and recipient in transplantation. Canadian doctors have developed a quick method to change the blood type of a transplant within hours, making it compatible with more patients.

Lungs being treated with an enzyme cocktail to remove antigens from red blood cells and make them compatible with all blood types. Image Credit UHN

Researchers at the Toronto General Hospital Research Institute in Canada have succeeded in changing the blood type of an organ to be transplanted. In just four hours, the lungs changed their group from blood type A to type O. This is an important step towards making organ transplants compatible with all patients.

A transplant that is compatible with all patients thanks to enzymes

Before transplanting an organ, doctors must make sure that it is compatible with the recipient to avoid graft rejection. The donor’s blood type must be compatible with the recipient’s blood type. For patients with a rare blood type, such as B- or AB+, the waiting time can be very long, which can be detrimental to their survival. To solve this problem, Canadian researchers have developed a technique to remove the A blood group antigens expressed by the red blood cells present in a lung transplant.

The operation takes place ex vivo, outside the body, under a plastic dome. The graft is perfused with a cocktail of two enzymes: FpGalNAc deacetylase and FpGalactosaminidase. “This group of enzymes, which we find in the human gut, can cut the sugars from the A and B antigens in red blood cells and convert them into universal O cells,” explains Stephen Withers, a member of the research team and affiliated with the University of British Columbia in Vancouver.

The goal of these preliminary tests is to ensure that the enzyme cocktail removes the A antigens from the red blood cells and does not damage the graft. The enzymes, concentrated at only 1 µg/ml, removed 99% and 90% of the A antigens from the red blood cells and the aorta, respectively. A total of eight lungs were subjected to the same treatment with promising results: on average, 97% of the A antigens were removed after four hours of treatment without any observable toxicity.

Without surface antigen, the graft appears as blood group O and becomes virtually universal, i.e. compatible with all blood groups. No human has yet been transplanted with an organ treated according to this protocol, so there is still a lot of unknown information about the organ’s viability and the body’s response. But the researchers simulated a transplant between normally incompatible people. The infusion of blood from group O into the former lung of group A – now universal – produced no side effects.