A genetically edited pig kidney functioned inside a brain-dead human for 61 days. Published in Nature, NYU Langone researchers performed multi-omics profiling of both the xenograft and the host's blood throughout the procedure, tracking every immune response in molecular detail. The kidney produced urine, filtered waste, and maintained stable renal function without proteinuria — it worked as a kidney.
Then the immune system noticed. Between postoperative days 10 and 28, blood plasmablasts, natural killer cells, and dendritic cells increased. B cell clonotypes expanded. By day 33, biopsy confirmed antibody-mediated rejection. The researchers treated the rejection, reversed it, and the kidney continued functioning through day 61.
The structural insight is about what “working” means in transplantation. The pig kidney worked as an organ. It failed as a resident. Organ function and immune acceptance are independent properties — you can have perfect physiology with active rejection, and the rejection can be managed without losing function. The 61-day result doesn't show that pig kidneys can replace human kidneys permanently. It shows that the functional gap is already closed. The remaining gap is immunological: convincing the host's immune system that the organ belongs. These are different problems with different solution spaces, and knowing which problem remains is the entire contribution. Before this study, it wasn't clear whether pig kidneys could sustain human physiology at all. Now the question is narrower and more tractable: not whether the organ works, but how to make the immune system stop noticing.