A blood type A kidney was converted to universal type O and transplanted into a human for the first time. The organ functioned for two days without acute rejection, the type of immune reaction that can destroy an incompatible transplant within minutes. We talked about it very recently, we now have (and give you) some more details.
The result, published Nature Biomedical Engineering, comes from a collaboration between theUniversity of British Columbia and Chinese hospitals. The technique uses enzymes that remove type A antigens from the kidney's blood vessels, transforming it into a universal donor. In Italy, one person dies every two days waiting for a kidney; in the United States, that number is as high as 11 a day. This breakthrough could change everything.
How molecular scissors work
Your blood type is determined by antigens on the surface of your cells. It's like a label that tells your immune system who you are. If your kidney has type A antigens and the recipient has type O, the body sees the organ as foreign and attacks it. The classic solution is to suppress the patient's immune system for days, with heavy treatments that increase the risk of infections and bleeding. Or wait years for a compatible kidney to arrive.
The team led by Stephen Withers of University of British Columbia, Together with Turun Song of the West China Hospital e Keqin Zhang ofChongqing University, reversed the problem. Instead of modifying the patient, they modified the organ. The enzymes developed in Vancouver act like molecular scissors: they cut the A antigens from the blood vessels of the kidney, leaving only the neutral base that characterizes the O group.
"It's like removing red paint from a car and revealing the neutral primer underneath," Withers explains with a fitting metaphor. "Once that's done, the immune system no longer sees the organ as foreign."
The converted kidney was called ECO kidney (Enzyme-Converted type-O). Conversion occurs during hypothermic perfusion, when the organ is kept in a machine that circulates oxygenated fluid at a controlled temperature. The enzymes work for hours, systematically removing all accessible A antigens.
The first test on humans
The transplant was performed in China on a 68-year-old brain-dead man, with family consent. The patient had blood type O and high levels of anti-A antibodies. exactly the kind of scenario that would normally lead to a sudden rejectionThe converted kidney was transplanted using standard clinical protocols.
For two days, the organ functioned perfectly. There were no signs of hyperacute rejection, that violent reaction that can destroy an incompatible transplant in minutes. The kidney produced urine, and the parameters were stable. On the third day, some markers of the original group A reappeared, triggering a mild immune reaction. But the damage was much less severe than a typical incompatibility, and researchers have observed signals that the body was beginning to tolerate the organ.
Why Group O is a problem
More than half of those on the kidney transplant waiting list have blood type O. The paradox is that type O kidneys, being universal donors, are also assigned to patients with other blood types. The result: those with type O must wait for an O kidney to arrive and not be given to someone else.
The data is clear. Patients with type O wait two to four years longer compared to other groups. In the United States, 11 people die every day waiting for a kidney transplant, and the majority are waiting for a type O organ. In Italy, according to the Transplant Foundation, waiting times vary significantly by blood type, with O and A patients facing the longest waits.
If any kidney could be converted to type O, the problem would be solved. More usable organs, shorter waiting lists, less waste. Any type A, B, or AB kidney could become universal.
The numbers of the transplant crisis: More than 3.500 Canadians and 100.000 Americans are on the waiting list for a lifesaving transplant. Many organs are rejected due to blood type incompatibility. With enzymatic conversion, these organs could be recovered and used.
What happens next
The fact that some A antigens reappeared on the third day isn't necessarily a problem. It indicates that the organ's cells continue to produce antigens, but the immune reaction was manageable. Cell sequencing showed an elevated expression of genes related to accommodation, the process by which the body learns to tolerate a partially incompatible organ.
The next step is to obtain approval for clinical trials on living patients. The startup Avivo Biomedical, spin-off of the University of British Columbia, is developing enzymes for commercial application. The goal is not only kidney transplants but also the creation of universal blood for transfusions.
“This is what happens when years of basic research finally connect to patient care,” Withers comments. “Seeing our discoveries come closer to real-world impact is what drives us forward.”
Precedents and alternatives
This isn't the first time an attempt has been made to circumvent the incompatibility problem. The enzymes to convert blood from type A to type O were identified in 2019 by the same team. In 2022, they demonstrated that a type A lung could be converted to type O, but the organ hadn't been transplanted into a human. Cambridge researchers had successfully modified three human kidneys, but without proceeding with the transplant.
At the same time, other teams are exploring different avenues. Some are working on genetically modified pig kidney transplants (xenotransplants), some are developing new antibodies to block rejection, and some are trying to growing kidney stem cells from urine to avoid transplants altogether. All this research is moving toward the same goal: making more organs available to more people.
But enzymatic conversion has a practical advantage: It works with organs from deceased donors, does not require preparation of the recipient, and can be integrated into existing protocols without distorting proceduresIf clinical trials confirm its long-term safety and efficacy, it could become the standard.
The future of transplants
It remains to be seen how long the conversion will last. The A antigens began to reappear after two days: the technique will need to be optimized to make it more durable, or strategies developed to manage antigen regeneration. Perhaps with additional doses of enzymes, perhaps with targeted immunosuppressive therapies.
But the principle is proven. Changing the organ instead of the patient works. It's no longer science fiction, it's applied chemistry. A kidney can be reprogrammed, its molecular identity altered, and the body will accept it. At least for a while. At least long enough to pave the way.
Ten years of research, dozens of experiments, a seemingly simple idea that clashes with the complexity of the human immune system. Now we have proof that it is possibleThe rest is engineering: refining, scaling, making accessible.
The waiting lists are long. People continue to die waiting. Maybe this is a way out. Or maybe just a piece of the puzzle. It needs to work on the hundredth day, not just the second. But in the meantime, for two days, an impossible kidney worked. And that's what matters.
