In a plastic-domed case at the Toronto General Hospital Research Institute, researchers gave a new identity to a pair of lungs. When the lungs first arrived at the lab, they came from someone with type A blood, which means certain tiny markers called antigens were attached to the lung tissue and blood cells. But by the time the lungs left the lab, those antigens had almost completely disappeared. In just an hour, the researchers had effectively converted the lungs to Type O.
“This is absolutely amazing,” says Aizhou Zhang, a researcher in the Cypel Lab at the University of Toronto and first author of a paper published inside this week Science Translational Medicine that describes 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 those most in need cannot get help because of a big problem: their blood type does not match the available organs.
Zhang works in a lab run by Marcelo Cypel, the article’s lead author and a thoracic surgeon who has spent years finding ways to increase the number of lungs available for transplants. One of his earlier innovations was the development of ex vivo lung perfusion (EVLP), the plastic dome device that gave the lungs in this study their new identity.
The device allows doctors to deliver nutrients and oxygen to donated lungs in a protected environment, improving their ability to transplant. Unlike organs, which are placed on ice after a donor has been harvested and then taken directly to the operating room, inside the EVLP the lungs warm up and their metabolism resumes before being transplanted. Doctors can then reassess lung function and use EVLP to administer drugs that improve the organ’s quality and salvage slightly damaged lungs that previously might not have been able to be used. “We brought the lungs back to life on this machine,” says Cypel, who thought this technology could also be used to modify the organ and turn it into an organ that could be conceived by a person of any blood type.
There are four major blood groups: A, B, O, and AB. Think of Type O as the base model. It has no antigens attached to it. The A and B blood groups each have additional antigens that attach to this nucleus, and AB blood contains both types of antigens.
For an organ transplant to work, the donor and recipient must have compatible blood types. For example, if someone with blood type O or B receives a donation from someone with blood type A, those A antigens trigger the recipient’s immune system to attack the transplanted organ, which is perceived as a foreign invader. This process, called rejection, can be deadly.
However, since blood of blood group O contains no antigens, people with O are considered “universal donors”. Your blood and tissues do not elicit an immune response in recipients of any blood type.
Cypel hoped that increasing the number of universal donors would make more lungs available to more people and make the process fairer. “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 match the person’s blood type, they may be the wrong size for them. Too small and they don’t deliver enough oxygen. Too big and they don’t fit the chest properly.
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