Researchers have successfully altered the blood type of three donor kidneys in a gamechanging discovery that could significantly improve the chances of patients waiting for a transplant finding a match.
The development could increase the supply of kidneys available for transplant, particularly within minority ethnic groups who are less likely to find a match, scientists say.
A kidney from someone with blood type A cannot be transplanted to someone with blood type B, nor the other way around.
But changing the blood type to the universal O would allow more transplants to take place as this can be used for people with any blood type.
University of Cambridge researchers used a normothermic perfusion machine – a device that connects with a human kidney to pass oxygenated blood through the organ to better preserve it for future use – to flush blood infused with an enzyme through the deceased donor’s kidney.
The enzyme removed the blood type markers that line the blood vessels of the kidney, which led to the organ being converted to type O.
Serena MacMillan, a PhD student at the University of Cambridge, said: “Our confidence was really boosted after we applied the enzyme to a piece of human kidney tissue and saw very quickly that the antigens were removed.
“After this, we knew that the process is feasible, and we just had to scale up the project to apply the enzyme to full-size human kidneys.
“By taking B-type human kidneys and pumping the enzyme through the organ using our normothermic perfusion machine, we saw in a matter of just a few hours that we had converted a B-type kidney into an O type.
“It’s very exciting to think about how this could potentially impact so many lives.”
People from minority ethnic groups often wait a year longer for a transplant than white patients, and so the study could have particular implications for them, experts say.
People from minority communities are more likely to have type B blood and with low donation rates from these populations there are not enough kidneys to go around.
In 2020-21, just over 9% of total organ donations in the UK came from black and minority ethnic donors while black and minority ethnic patients make up 33% of the kidney transplant waiting list.
Now the researchers need to see how the newly changed O-type kidney will react to a patient’s usual blood type in their normal blood supply.
The machine allows them to do this before testing in people, as they can take the kidneys that have been changed to type O, and introduce different blood types to monitor how the kidney might react.
Prof Mike Nicholson, professor of transplant surgery at the University of Cambridge, said: “One of the biggest restrictions to who a donated kidney can be transplanted to is the fact that you have to be blood group compatible.
“The reason for this is that you have antigens and markers on your cells that can be either A or B.
“Your body naturally produces antibodies against the ones you don’t have.
“Blood group classification is also determined via ethnicity and ethnic minority groups are more likely to have the rarer B type.”
Dr Aisling McMahon, the executive director of research at Kidney Research UK, said: “The research that Mike and Serena are undertaking is potentially gamechanging.”
After testing the reintroduction of other blood types, the team will look at how the approach might be used in a clinical setting.
The research, which is funded by charity Kidney Research UK, is due to be published in the British Journal of Surgery in the coming months.