On January 7, 2022, surgeons at the University of Maryland Medical Center transplanted a genetically modified pig heart into 57-year-old David Bennett, marking the first pig-to-human heart transplant and a milestone in xenotransplantation (cross-species organ transplantation). Bennett, dying from heart failure and ineligible for a human heart transplant, survived two months before dying on March 8, 2022—far longer than expected but revealing challenges in using animal organs to address the critical shortage of donor organs (17 people die daily in the US waiting for transplants).
The Genetically Modified Pig
The pig heart came from a Virginia-based company (Revivicor) that had made 10 genetic modifications: four pig genes were knocked out (including ones that produce sugars triggering human immune rejection and genes causing continued heart growth), and six human genes were inserted (to improve immune compatibility and prevent blood clotting). The modifications aimed to trick the human immune system into accepting the foreign organ as “self.”
The Two-Month Survival & Complications
Bennett initially recovered well enough to watch the Super Bowl from his hospital bed and communicate with family. However, his health declined in late February 2022, and he died in early March. Autopsy revealed several contributing factors: signs of organ rejection despite heavy immunosuppression, possible cytomegalovirus (CMV) infection carried by the pig heart (later confirmed via genetic testing), and Bennett’s severely weakened state before surgery. The virus finding raised questions about whether better pathogen screening could have prevented complications.
Xenotransplantation Future
Despite Bennett’s death, the transplant proved genetically modified pig hearts could function in humans for weeks—far beyond the hours or days seen in earlier primate experiments. In 2023, researchers performed experimental pig kidney and heart transplants into brain-dead human subjects, gathering data without risking living patients. The eventual goal: industrial-scale “organ farms” producing genetically modified pig organs on demand, ending transplant waitlists. Challenges remain: immune rejection, virus transmission risks, ethical concerns about raising animals for organ harvest, and unknown long-term compatibility.
Sources: University of Maryland Medical Center press releases (January-March 2022), MIT Technology Review xenotransplantation coverage, Nature Medicine autopsy analysis, Revivicor genetic modification disclosures