Changing the blood type of donated organs could shorten transplant wait times. //

In a plastic-domed case 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 were from someone with type A blood, meaning that there were certain tiny markers, called antigens, attached to the lung tissue and blood cells. But when the lungs left the lab, those antigens were almost entirely gone. In just one hour, the researchers had effectively transformed the lungs into type O. //

There are four major blood type groups: A, B, O, and AB. Think of type O as the base model. It has no antigens that attach to it. The A and B blood types each have extra antigens that attach to that core, and AB blood has both types of antigens.

For an organ transplant to work, the donor and recipient have to have compatible blood types. If someone with type O or B blood receives a donation from someone with type A blood, for example, those A antigens will 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.

But because type O blood has no antigens, people with O are considered “universal donors.” Their blood and tissue won’t set off an immune response for recipients of any blood type. //

This study is just a proof of concept, meant to show that such a feat is possible, cost-effective, and takes effect quickly enough to work in a real-life transplant scenario. But they didn’t try transplanting the tissue, and they focused their work on only the A antigen. (The team is currently looking for the right enzymes to perform that same search-and-snip function on B antigens.) One question is whether the body will immediately reject the modified lung. Another is whether those A antigens will regrow and trigger that dangerous immune response when they do.