External research · Kidney xenotransplantation

Robert Montgomery’s pig-to-human kidney xenotransplant studies

Two studies in human decedents: 54 hours in 2022 and 61 days in the later report. Here are the findings, limits and correction notices.

BHOC Transplant evidence brief · Updated

Evidence boundary These are external pig kidney transplant studies. Neither tested BHOC or an oxygen-carrier perfusate.

01 / NEJM · 2022

Two cases, 54 hours

Results of Two Cases of Pig-to-Human Kidney Xenotransplantation ↗Montgomery RA, Stern JM, Lonze BE, et al. · Published 19 May 2022

Research model
Two people with established brain death received genetically modified pig kidney xenografts.
Observed
The grafts produced urine. During 54 hours, biopsies showed no evidence of hyperacute or antibody-mediated rejection.
What this cannot show
Durable graft function, long-term safety or outcomes in living recipients. PubMed record ↗
02 / Nature · 2025/26

One case, 61 days

Physiology and immunology of a pig-to-human decedent kidney xenotransplant ↗Montgomery RA, Stern JM, Fathi F, et al. · Online 13 November 2025; issue 5 February 2026

Research model
One person with established brain death received a gene-edited pig kidney. Observation continued for 61 days.
Observed
The report describes dialysis independence. Antibody-mediated rejection developed on day 33 and was reported as reversed after treatment.
What this cannot show
The 61 days were not rejection-free. One decedent study cannot establish long-term outcomes in living recipients or be compared directly with the 2022 study. PubMed record ↗

Nature corrections

Two correction notices amend the Nature article. They are not additional studies.

The publisher notice corrects figure-axis units and an IgG label to IgM. Use the corrected version when reading those figures.

BHOC research hypothesis

A separate question about organ support

Neither study answers whether a characterized oxygen carrier could support kidney graft function during ex-vivo preparation. That question would need its own protocol, comparator, organ-specific endpoints and safety assessment. Xenograft findings are not evidence of BHOC efficacy in recipients.

Sources and review scope

  1. Montgomery et al., NEJM (2022): doi:10.1056/NEJMoa2120238 ↗.
  2. Montgomery et al., Nature (online 2025; issue 2026): doi:10.1038/s41586-025-09847-6 ↗.
  3. Publisher Correction ↗ and Author Correction ↗ (2026).

This is an editorial summary of publication records, abstracts and correction notices. It is not a systematic review or an analysis of raw data. Evidence method ↗