The Pig/Human Kidney Connection: Is it a Match Made in Heaven or a Medical Version of “Love is Blind?"

Andrew Kowalski, MD, FASN

I was reading through apple new this weekend and stumbled upon a interesting article. WIRED Magazine published an article by Emily Mullin:

A Transplanted Pig Kidney Is Still Working After a Record-Setting 9 Months in a Patient

Without a doubt it caught my eye! It also had me reflect on the progress that we (the medical/Kidney Community) have made over the last 5 years.

Truly astonishing!

A woman transplanted with a gene-edited porcine kidney at Massachusetts General Hospital on November 22, 2025 has now gone 285 days with a functioning graft and without dialysis, the longest anyone has lived with a pig kidney. She is the 5th recipient of eGenesis' EGEN-2784 organ under an FDA Expanded Access protocol, and the previous mark of 271 days, set by Tim Andrews.

The wider dataset matters more than the single case. eGenesis reports that five patients have received EGEN-2784 kidneys under Expanded Access with Mass General Brigham since March 2024, and three have sustained kidney function beyond eight months without dialysis. That shift, from isolated survivors to a small cohort with reproducible function, is what moves this from curiosity to signal. The organ carries 69 genomic alterations: roughly ten knocked out or added to blunt immune rejection and clotting, plus 59 endogenous retroviral sequences inactivated, paired with investigational immunosuppression from Apellis and Eledon rather than a conventional regimen.

As Emily Mullin clearly points out, the clinical argument being made is a dialysis-avoidance argument, and it is one your patients will recognize immediately. FDA has cleared a Phase 1/2/3 study (RESTORE) enrolling 33 waitlisted patients aged 50–70, with initiation expected in Q1 2027, and United Therapeutics is running a parallel program with its UKidney at NYU Langone, where participants are followed for 24 weeks and then for life, including surveillance for zoonotic infection. 

With all the excitement around this new adventure in medical science, zoonotic infections remain a serious concern.

Zoonotic infections are diseases caused by viruses, bacteria, parasites, or fungi that can spread between animals and humans. Some are transmitted through direct contact with an infected animal, while others spread through bites, contaminated food or water, animal waste, or insects such as mosquitoes and ticks. These infections are not unusual to humans or animals, which means microorganisms occasionally cross from one species into another.

The greatest concern with zoonotic infections is the possibility that a microorganism that normally circulates in animals could adapt well enough to infect humans and then begin spreading efficiently from person to person. This process is sometimes called a “spillover” event. Most spillover infections do not lead to major outbreaks because the organism cannot easily transmit between humans. However, when a pathogen is both capable of causing significant illness and able to spread efficiently, it has the potential to produce a much larger public-health problem. And to be fair these senarios have happened already.

• Ebola: believed to spill from wildlife reservoirs into humans through contact with infected bats or nonhuman primates.

• Hantaviruses: humans can become infected after inhaling particles contaminated with urine or droppings from infected rodents

• Avian influenza viruses such as H5N1: primarily circulate in birds but can occasionally infect humans, usually after close exposure to infected poultry or contaminated environments

• Swine influenza viruses: the famous scare prior to COVID-19, can similarly jump from pigs into humans

• MERS-CoV: is a classic example of a coronavirus spillover infection. The virus is associated with dromedary camels and has repeatedly infected humans

• SARS-CoV-1: Not the recent pandemic, but the virus responsible for the 2002–2004 SARS outbreak, is also thought to have originated in bats

• Rabies: which spills over to humans through bites from infected mammals

• Monkeypox/mpox: which can move from infected animals into humans and can then spread person to person

• Lassa fever: which is transmitted to humans from infected rodents.

The important distinction is that a spillover event does NOT automatically mean a pandemic. Many of these infections infect only a small number of people and then stop. Most likely because the pathogen is poorly adapted to human-to-human transmission.

Public-health concern rises sharply when three things occur together:

1. The organism can infect humans

2. It causes significant disease

3. It becomes capable of sustained transmission between people.

Key points

1. 285 days of graft function, dialysis-free, single patient, MGH. Prior record 271 days. Three of five expanded-access recipients past eight months.

2. Two independent xenokidney programs now hold FDA INDs. Formal trials, not compassionate use, begin 2026–2027.

3. The improvement across recipients tracks better patient selection as much as better organs. Andrews was a relatively well dialysis patient who deliberately conditioned himself to qualify; the earliest recipients were far sicker and did far worse.

4. The intended positioning is a bridge, not a destination, dialysis-free time while remaining on the human waitlist.

Concerns worth naming

1. The were only five individuals. No control arm, one health system, company-issued press releases rather than peer-reviewed outcomes. We have no published eGFR trajectories, proteinuria data, or protocol biopsy findings for these grafts.

2. Every pig kidney so far has eventually failed. Andrews' organ was removed at 271 days for declining function and he returned to dialysis; an earlier recipient's graft lasted 130 days. In terms of deceased-donor allograft (human to human) survival measured in years, nine months is a milestone, not a therapy.

3. The immunosuppression is as experimental as the organ. Current anti-rejection agents are not approved for transplant maintenance. Infection and malignancy risk over years is unknown, and the regimen cannot be replicated outside a trial. A huge unknown.

4. Sensitization is the unanswered nephrology question. If a xenograft primes antibody responses in the recipient, a failed pig kidney could make the subsequent human transplant harder to get. The truth is we really don't know, nobody has published on this adequately.

5. Generalizability and equity. Trial criteria are age 50–70, dialysis-dependent, waitlisted, and functionally well enough to survive major surgery. That excludes most of the frail and the majority of the dialysis population.

To be VERY CLEAR, THIS IS REAL PROGRESS! Although, not available outside a research protocol. The single most effective choice, and next step, a patient can do this year is still to complete transplant evaluation and pursue living donation.