Pig kidneys kept at subzero temperatures for three days show faster recovery than standard storage

Researchers at Texas A&M University have successfully transplanted kidneys stored at -4°C (25°F) for up to 72 hours into pigs, demonstrating that supercooled organs recover function faster than kidneys kept on traditional ice, according to work presented at the American Transplant Congress in Boston.

The advancement targets a persistent bottleneck in organ transplantation: time. Standard cold storage keeps organs at around 4°C (39°F) for approximately 24 hours before viability degrades. In the US alone, more than 104,000 people are waiting for kidney transplants, with an estimated 17 dying daily while waiting. Around one in three donated kidneys are discarded annually because they deteriorate before reaching a suitable recipient.

Matthew Powell Palm, a thermodynamicist at Texas A&M, designed a hermetically sealed device that maintains organs submerged in a preservation solution at constant pressure. This prevents ice crystal formation—the primary obstacle to freezing large organs—without requiring cryoprotective chemicals that carry regulatory uncertainty.

In the pig studies, kidneys supercooled for 24 hours began producing urine immediately after transplantation and showed normal function within about 10 days. Organs stored for 48 and 72 hours recovered similarly, though slightly slower than those stored for just two hours on ice. Powell Palm noted that even at three days, "recovery is faster than [what has been] the gold standard for the last three decades."

Heidi Yeh, a transplant surgeon at Mass General Brigham for Children who researches organ preservation, called the results impressive. "Often kidneys stored for 48 hours take a week or two before they start working again," she said.

Long-term outcomes appeared robust. Pigs monitored for 30 days showed the transplanted kidneys growing alongside the animals' own growth—nearly doubling in size to compensate for a missing second kidney. One organ was tracked for 200 days and remained healthy.

Kevin Myer, president and CEO of LifeGift, an organ procurement organization based in Texas, described the work as "a landmark achievement." He emphasized practical implications: extending the preservation window to 72 hours would allow surgeons more time to evaluate kidneys, match donors, arrange transport, and potentially enable international donations. "If we can get up to 72 hours," Myer said, "that would change everything."

Preliminary data suggests the team may extend preservation further—organs stored for up to 120 hours appeared healthy, though transplantation trials have not yet occurred. Because the method avoids chemical additives, Powell Palm's team is seeking accelerated FDA approval.

Canadian researchers reported separate progress earlier this year, achieving subzero cooling and short-term survival of pig kidneys using a cryoprotectant-based protocol, though organs were stored only up to 48 hours.