Scientists have achieved a major breakthrough in organ transplantation by successfully converting a type A kidney into a universal type O donor kidney and transplanting it into a human recipient for the first time. The groundbreaking procedure, conducted by researchers from Canada and China, could revolutionize organ transplantation by eliminating blood type compatibility as a barrier to donation.
The research team, led by chemist Stephen Withers from the University of British Columbia in Vancouver, Canada, used specialized enzymes to remove type-A antigens from a donor kidney. The converted type-O kidney was then transplanted into a 68-year-old brain-dead man in Chongqing, China, where it remained healthy for two days before showing signs of rejection and produced urine for six days.
Addressing the Organ Shortage Crisis
The innovation directly addresses one of the most pressing challenges in transplant medicine. In the United States alone, more than 90,000 people are currently on the kidney transplant waiting list, with nearly half having type O blood. These patients face the longest wait times, often waiting 2-4 years longer for a compatible kidney because they cannot accept kidneys from types A, B, or AB donors.
"Here we present a donor-centric desensitization protocol, converting type-A kidneys into enzyme-converted O kidneys during hypothermic perfusion to remove the A antigen from the kidneys," the researchers explained. "An ex vivo model resulted in no antibody-mediated injury. Encouraged by this, an enzyme-converted O kidney was transplanted into a type-O brain-dead recipient with a high titre of anti-A antibody, and no hyperacute rejection was observed."
The Science Behind Blood Type Conversion
Blood type compatibility is crucial in organ transplantation because antigens on blood cells and organs determine whether the recipient's immune system will accept or reject the donated organ. Type O organs are considered universal donor organs because they lack the main A and B antigens, making them compatible with any recipient.
The conversion process involves treating the donor kidney with enzymes that specifically target and remove the A antigens responsible for the A blood type. During the procedure, the kidney undergoes enzyme perfusion for approximately two hours, during which the enzymes cut away the antigens that would otherwise trigger immune rejection. The organ is then preserved using standard transplant techniques until surgery.
Clinical Implications and Future Potential
Natasha Rogers, a transplant clinician at Westmead Hospital in Sydney, Australia, described the results as groundbreaking, noting they could improve access to donor organs and reduce transplant wait lists. "If the blood type of the organ was no longer a barrier for transplantation, physicians could focus on things such as matching other antigens unrelated to blood type, which are important in terms of how long a transplant will last," Rogers explained.
The technique builds on previous research by the same team, who first identified the enzyme in 2019 and demonstrated in 2022 that a type-A lung could be converted into a type-O organ, though that organ wasn't transplanted into a person.
Current Limitations and Next Steps
While the initial results are promising, the research revealed important limitations that need to be addressed. The antigen removal proved temporary, with some antigens returning over time, leading to eventual rejection. Additionally, the procedure has only been tested in a brain-dead recipient, not yet in a living patient.
Future studies will focus on combining the enzyme conversion process with standard anti-rejection medications used in transplant medicine to potentially extend the effectiveness of the converted organs. The research team is also exploring applications for other organs, having already tested the enzyme-based method on lungs in laboratory settings, with hopes to apply it to hearts and livers in the future.
This breakthrough represents a significant step toward creating truly universal donor organs, potentially transforming the landscape of organ transplantation and offering hope to thousands of patients currently facing lengthy waits for compatible organs.