A Pig Kidney Kept a Human Alive in 2024. eGenesis Made It Possible

Seventeen people die every day in the United States waiting for an organ transplant. Not from their disease progressing. From waiting.

In 2024, a team at Massachusetts General Hospital transplanted a gene-edited pig kidney into a living human patient named Richard Slayman. His immune system didn't reject it. The organ worked. What had been a theoretical frontier in medicine became a clinical reality—and Cambridge-based eGenesis built the biology that made it happen.

Why Human Donor Organs Can't Meet Demand

Over 100,000 Americans sit on the national transplant waitlist at any given moment. Kidneys account for the largest share—83,000 patients waiting for a single organ that determines whether they spend three days a week connected to a dialysis machine or live normally. Many wait five to ten years. Many don't make it.

The core problem isn't surgical skill or hospital capacity. It's supply. Human donor organs are scarce by definition. A transplant requires a matching donor, compatible blood type, compatible tissue type, and timing that aligns availability with medical urgency. Every one of those conditions must align simultaneously. Most often, they don't.

Researchers have explored xenotransplantation—transplanting organs across species—for decades. Pigs emerged as the most promising donors because their organs are anatomically similar to humans in size and function. But pig organs carry genetic markers that human immune systems immediately recognize and attack. They carry pig viruses that could transfer to human recipients. They produce proteins that trigger catastrophic rejection responses within minutes of transplant.

Biology built a wall between pigs and people. CRISPR-based gene editing gave eGenesis the tools to take it apart brick by brick.

The 2024 Milestone That Changed Everything

Richard Slayman had received a human kidney transplant years earlier. When that kidney began failing, he faced the prospect of returning to dialysis while waiting—again—for another human donor.

Instead, surgeons at Massachusetts General Hospital transplanted an eGenesis genetically engineered pig kidney in March 2024. The procedure lasted approximately four hours. In the days that followed, Slayman's new kidney functioned. His body didn't mount the catastrophic rejection response that had ended every previous long-term xenotransplantation attempt in humans.

The procedure wasn't just a surgical achievement. It was a proof of concept that 69 genetic edits—carefully designed over years of research by eGenesis scientists—could produce an organ compatible enough with human biology to sustain life outside a laboratory setting.

Dr. Tatsuo Kawai, the transplant surgeon who led the procedure at Massachusetts General, described it as a critical step toward making xenotransplantation a viable clinical option. The clinical data generated from Slayman's procedure now informs eGenesis's next research phase and regulatory conversations with the FDA about the path toward larger clinical trials.

What Success at Scale Would Mean

A reliable supply of transplantable pig organs would restructure how organ failure is treated globally.

Today, transplant timing depends on donor death. A patient deteriorates. A compatible donor dies. The surgical team scrambles to match supply and demand in a window measured in hours. Surgeons operate in the middle of the night because that's when the organ became available, not because it's optimal for the patient.

Gene-edited pig organs from eGenesis could be produced, screened, characterized, and made available on predictable schedules. Transplant programs could plan procedures rather than react to them. Patients who currently don't survive long enough to reach the top of the waitlist could receive organs sooner—years sooner in many cases.

Kidneys represent the most immediate opportunity because dialysis serves as a temporary bridge, keeping patients alive while they wait. But eGenesis's research extends to hearts and livers—organs with no equivalent bridge therapy. Patients with end-stage heart failure who don't receive a transplant within months face near-certain mortality. A reliable alternative source changes that calculus entirely.

The company completed a $191 million funding round in 2023, supported by investors who include ARCH Venture Partners and Byers Capital. That capital funds the expanded genetic research, animal husbandry infrastructure, and clinical study design required to move from a single landmark case toward regulatory-approved standard treatment.