A breakthrough in kidney transplants

A new method could help aid donor compatibility in organ transplants
18 August 2022

Interview with 

Serena MacMillan, University of Cambridge




This week a huge leap forward has been made in potentially making organs for transplant accessible to more people.The NHS estimates there to be around 7000 people on the UK Transplant Waiting List. Last year, over 420 people died while waiting for a transplant. A large number of those on the waiting list will be those suffering from kidney failure. So why can’t anyone donate one of their kidneys to someone in need? Well, it comes down to blood type. Someone with type A can’t donate to someone with type B, and vice versa. But, now, researchers from the University of Cambridge may be well on the way to bypassing this problem: they’ve converted a B-type kidney into an O-type…

Serena - So the waiting time for a kidney is disproportionately large, if you're a blood group O or B, and that's due to the fact that you said you need this compatibility between the different blood group types. So because type B can only receive a type B or O organ, and type O can only receive O, they wait a bit longer because there's a lower percentage of those kidneys being available to them. Whereas in the UK, a lot of people are group A as well, so you end up with a higher proportion of kidneys available for people with that blood group, for example. So, sadly for people who are blood group O and B, you're waiting typically twice as long as if your blood group a at the moment.

Julia - Big difference there, what was the work that you've done to try and help combat this?

Serena - So, yeah, our lab specializes in something called normothermic machine perfusion, which sounds very complicated, but is actually really simple. So basically we take a donor kidney and are able to pump it full of blood outside of the body. Now, what we were able to do with this is introduce an enzyme which works like a pair of molecular scissors, and that removes this A or B type from the surface of the cells of the kidney. So we can apply these molecular scissors to an organ outside the body, and then basically remove the antigens or markers that are causing that lack of compatibility.

Julia - So what effects could this work actually have?

Serena - Yes, that's a really exciting thought for this kind of early stage work, but the real take home message from this is that we might be able to remove this ABO barrier completely from transplantation. The future goal is to be able to make any kidney of any blood group accessible to any recipient, so that the next kidney that comes on the list isn't for a particular blood group or a person who's A or person is B. It just goes to the next person. So the hope is that we're able to introduce this sort of technique and hone it down to make it work as well as we can, and then potentially allow a better allocation and distribution of the donor kidneys that are available.

Julia - Is blood group the only measure of compatibility that you have to have when you're trying to match someone up with a potential organ for transplant.

Serena - So, no, if you imagine it as a series of hurdles, then there are quite a few. There's the ABO compatibility. There's something called HLA compatibility as well, which is to do with tissue typing. And while the blood group compatibility isn't the only barrier, it's still getting rid of one of the hurdles. So you're able to already bypass potentially one of the key restrictions to allocating a donor kidney. Our work is purely based on this part of the moment, but future research, who knows? We'll be able to make any kidney for anybody with no restrictions whatsoever. Wouldn't that be great?

Julia - That would be incredible. So do you think, we are talking about kidneys here, but obviously there are other organs that are required for transplantation. Do you think this has the potential to cross over from just the work you did for kidneys? The technique that you are using, would that work on other organs as well?

Serena - Absolutely. So there was a great paper from America last year - early this year, I should say, who did a similar thing, looking at lungs. So proof of principle in that organ, but equally being able to perfuse an organ outside the body. We can do it with the liver, we can do it with the heart. So it's all in terms of optimizing this therapy for the different organs, which obviously hasn't been tried yet, but the principle is definitely there.


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