CRISPR-Edited Pig Kidney Bridges Patient to Human Transplant

The central worry in xenotransplantation is not only whether a pig organ works, but whether rejecting one leaves the recipient primed against future human donors. The kidney, EGEN-2784, had been edited to lack the three glycan xenoantigens that drive hyperacute rejection, inactivate porcine endogenous retroviruses, and add seven human transgenes regulating complement, coagulation and inflammation. The recipient, who had no living donor and a long expected wait, received costimulation blockade with complement inhibition.

The graft worked immediately and kept the recipient dialysis-free for 271 days. An early episode of T-cell-mediated rejection was reversed, and function remained stable for about six months. After immunosuppression was reduced during a bacterial infection unrelated to the pig, microvascular inflammation and endothelial injury progressed to thrombotic microangiopathy, requiring removal of the graft. The damaged kidney contained mainly macrophages and natural killer cells, while crossmatch testing remained negative, suggesting injury not explained by conventional donor-specific antibody-mediated rejection alone.

Eighty-two days after the nephrectomy the patient received a deceased-donor human kidney, with immediate graft function and no evidence of sensitization during over 231 days of follow-up. This first case in a small expanded-access series suggests that xenotransplantation could serve as a temporary bridge rather than only as a permanent replacement.

The study was led by Leonardo Riella and Tatsuo Kawai at the Massachusetts General Hospital. It was published in The Lancet on 4 September 2026.