271 days off dialysis on a pig kidney, then a human transplant that worked

Design

First-in-human single-patient report under a US FDA expanded access investigational new drug application

Population

One adult with end-stage kidney disease, no suitable living donor and a long anticipated wait

Primary outcome

Graft function, zoonotic transmission, sensitisation, and outcome of subsequent human allotransplantation

Effect

271 days dialysis-free; day-14 T-cell-mediated rejection resolved; late thrombotic microangiopathy caused graft loss; no porcine pathogen transmission; anti-HLA antibodies unchanged; human allograft at 82 days functioned immediately over 231 days' follow-up

A patient with end-stage kidney disease, a long expected wait for a deceased donor and no living donor received a gene-edited porcine kidney at Massachusetts General Hospital in January 2025, under a US Food and Drug Administration expanded access application. The organ carried deletions of the major glycan xenoantigens, inactivated porcine endogenous retroviruses and seven human transgenes; immunosuppression was costimulation blockade with complement inhibition.

It worked immediately and held dialysis independence for 271 days. A day-14 biopsy showed T-cell-mediated rejection that resolved with treatment. Function stayed stable for about six months until immunosuppression was reduced during a bacterial infection, after which microvascular inflammation appeared and progressed to thrombotic microangiopathy, ending in graft failure and nephrectomy — with donor-specific crossmatch persistently negative and the infiltrate dominated by macrophages and natural killer cells rather than T cells.

The three questions the field had are each answered once here. No porcine pathogen transmission was detected. Anti-HLA antibodies did not change. And 82 days after explantation the patient received a human kidney that functioned immediately, with no sign of sensitisation over 231 days. That is the specific claim worth carrying: a xenograft can apparently be used and withdrawn without burning the bridge to a human organ.

• This is one patient in a planned three-patient study, not a trial result
• The bridging claim is the novel part: no allosensitisation and a successful subsequent allograft
• Late failure looked like macrophage and natural-killer-driven injury, not classical antibody rejection
• Nothing here changes waiting-list counselling anywhere today
• Note the immunosuppression reduction during infection as the point at which things turned

Why it matters

It tests whether a xenograft costs a patient their later chance at a human organ — and in this case it did not.

Don't overread it

This is a single case report under expanded access, not evidence that xenotransplantation is an option for patients.

The statistics, in plain English

There are no statistics here and that is the point: a single case cannot give a rate of anything — not graft survival, not infection risk, not sensitisation. Its value is that it can disprove a fear. The absence of detected pathogen transmission and of anti-HLA change in this one recipient does not establish that either is rare.

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