Kidney donor and recipient blood groups must be compatible

In kidney transplantation, the donor and recipient blood groups must be matched. If a kidney transplant is performed when the blood groups do not match, then immediate and irreversible rejection occurs, and the kidney is lost.

All people have one of four blood groups- O, A, B, or AB, depending on which sugar molecules, called antigens, coat the surface of their red blood cells. These antigens are also found on the surface of the cells that line blood vessels throughout the body, including in the kidney.

Blood group ‘O’ is the universal donor

All red blood cells have ‘H’ sugars on their surfaces and if this is the only antigen present then the blood group is O-type. Blood groups A, B and AB are formed when different extra sugars are added to the core H sugar antigen.

O-type kidneys are special and extremely in-demand because they can be used as a universal donor for any other blood type. But unfortunately, less than half of all donated kidneys are type O.

What if all kidneys could be engineered to be blood type ‘O’?

The researcher will investigate a novel way of changing the blood group of a kidney. They will use special proteins that can chop A and B sugars off the core H sugar to generate blood group O kidneys.

The team have already shown that this technique is possible in blood and in this project, they will test it initially on thin slices of human kidney in a dish, and then on whole human kidneys that have been turned down for transplantation and donated for research and this will form the basis for clinical trials.

After changing the blood group of a kidney using this novel technique, the researchers will pump blood of a different blood group through the kidney to check that rejection doesn’t occur.

What does this mean for kidney patients?

If this project is successful, it could have huge implications for transplantation. It could mean that every donor kidney could be converted into a group O-type organ with the potential to be transplanted into any patient on the waiting list. This would also be a huge step towards tackling health inequalities in access to transplant as Black, Asian and ethnic minority patients often have blood group B which means they currently have to wait for longer for a transplant as only 10% of donor kidneys are group B.

“My group has been fortunate enough to receive generous funding from KRUK for more than 10 years,” said Michael. “The award of a prestigious Kidney Research UK PhD studentship will further strengthen the Cambridge team that is investigating the use of ex vivo normothermic machine perfusion (NMP) in kidney transplantation. Highly efficient enzymes that can change group A and B blood into group O are now available. Our Kidney Research UK PhD student will apply this novel strategy to human kidneys by delivering enzymes during NMP to generate universal donor group O organs. This approach has the potential to change clinical practice by reducing the need for kidney exchange schemes and ABO incompatible transplants. This especially impacts ethnic minority groups who currently have reduced access to transplantation due to high prevalence of blood group B.”

Michael has been awarded a grant of £56,688 for two years from Kidney Research UK for a PhD student to carry out this work.