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In a plastic-domed enclosure at the Toronto General Hospital Research Institute, researchers gave a pair of lungs a new identity. When the lungs first arrived in the lab, they belonged to someone with type A blood, meaning certain small markers called antigens were attached to the lung tissue and blood cells. But when the lungs left the lab, those antigens were almost completely gone. In just an hour, the researchers had effectively transformed the lungs into type O.
“This is absolutely amazing,” said Aizhou Zhang, a researcher in the Cypel Lab at the University of Toronto and lead author of a paper published this week in Science Translational Medicine describing the transformation. The experiment is an important step in giving more people access to life-saving organ transplants. More than 100,000 people in the United States are currently waiting for organs, but often the most needy can’t get help because of one big problem: Their blood type doesn’t match the organs available.
Zhang works in a lab run by Marcelo Cypel, the paper’s lead author and a chest surgeon who has spent years looking for ways to increase the number of lungs available for transplants. One of his earlier innovations was the creation of ex vivo lung perfusion (EVLP), the plastic-domed device in which the lungs of this study were given their new identity.
The device allows doctors to provide donated lungs with nutrients and oxygen in a protected environment, improving the viability of their transplant. Unlike organs that are put on ice after being harvested from a donor and then sent straight to the operating room, the lungs in the EVLP warm up and begin their metabolism again before being transplanted. Doctors can then reassess the function of the lungs and use EVLP to deliver drugs that improve organ quality, saving slightly damaged lungs that were previously ineligible for use. “We’ve brought the lung back to life on this machine,” says Cypel, who thought this technology could also be used to modify the organ so that it can be received by a person of any blood type.
There are four major blood groups: A, B, O, and AB. See type O as the basic model. It has no antigens attached to it. The A and B blood groups each have additional antigens that attach to that nucleus, and AB blood has both types of antigens.
For an organ transplant to work, the donor and recipient must have compatible blood types. For example, if someone with type O or B blood receives a donation from someone with type A blood, those A antigens will prompt the recipient’s immune system to attack the transplanted organ, which is perceived as a foreign invader. This process, called rejection, can be deadly.
But because type O blood has no antigens, people with O are considered “universal donors.” Their blood and tissue will not trigger an immune response to recipients of any blood type.
Increasing the number of universal donors, Cypel hoped, would make more lungs available to more people and make the process more equitable. “Today we have a separate list of A patients, B patients, O patients, and we don’t necessarily transplant [to] the sickest,” he says. And even if a pair of donor lungs matches the person’s blood type, they may be the wrong size. Too small and they won’t provide enough oxygen. Too big and they don’t fit well in the chest.
