Scientists Convert Blood-Type A Kidney to Type O for Transplant
In an exciting advancement for organ donation, researchers have managed to transform a blood-type A kidney into a blood type O kidney, which was later transplanted into a brain-dead recipient.
This transformed kidney, effectively becoming a universal organ, functioned well for about two days before signs of rejection emerged. If further refined, this technique might reduce waiting times for those on organ donor lists.
The study, published recently in Nature Biomedical Engineering, elaborates on the successful conversion from type A to type O using specific enzymes, which serve as catalysts for biological reactions.
Since the 1950s, kidney transplants have offered a solution for patients suffering from renal diseases. However, organ transplantation is often complicated by the necessity of matching donor and recipient blood types, along with the challenge of locating a fitting organ nearby.
Humans possess four main blood types: A, B, AB, and O. Compatibility issues can arise because the immune system of someone with one blood type might react against another type. For instance, someone with type O blood can only accept a type O kidney, while those with A, B, or AB can also tolerate type O organs. This difference is due to the presence of immune-triggering substances, called antigens. Type O blood lacks these, allowing it to be universally accepted, while other types could provoke a reaction.
In the late 1980s, methods were developed to transplant ABO-incompatible organs into recipients, but this approach was labor-intensive and time-consuming. Then, in 2022, researchers introduced an enzyme-based protocol that could convert organs to a “universal” type known as enzyme-converted O (ECO).
Stephen Withers, a professor emeritus of biochemistry at the University of British Columbia, who was part of the team that developed the ECO technique for lungs, expressed optimism about its applicability to other organs. “We hope it works for all other organs — it should!” he commented.
In their latest work, Withers and colleagues used a kidney from a donor that wasn’t suitable for transplantation. They managed to convert it into a type O through a process that involved perfusing the kidney with a specialized fluid over about two hours.
Withers noted that perfusion devices are commonly utilized to preserve organs prior to transplantation. The process involved adding specific enzymes to the fluid to eliminate blood-group antigens that could trigger rejection.
The conversion helps prevent the organ from being recognized by anti-A antibodies present in the recipient’s bloodstream. While the procedure doesn’t permanently remove the problematic antigens, it may help mitigate the immune response initially.
To test whether the kidney could evade immediate rejection, the team transplanted the ECO kidney into a brain-dead patient whose family agreed to participate in the study. Unlike typical transplants, where recipients receive antibody therapy to prevent rapid rejection, the researchers opted against this treatment to evaluate the ECO kidney’s performance.
Over the first two days after transplantation, the kidney functioned properly, but on day three, it began to exhibit immune response signs as new A antigens emerged.
Withers pointed out, “In an actual clinical transplant, there are several techniques to reduce initial antibody-mediated rejection, including optimized immunosuppression.” If these procedures are applied to ECO kidneys, it may allow for longer-term acceptance of the transplant.
Transforming organs to different blood types could significantly enhance access for patients needing transplants, especially considering that over 50% of those on waiting lists are type O candidates, often facing longer waits than others.
Although this pioneering transplant was successful, the process is still in its developmental phase. Withers acknowledged the uncertainty of whether this method will be widely applicable, saying, “However, it is certainly a possibility.”
