Iron Oxide Nanoparticles Enable Revival of Pig Kidneys After a Year of Cryopreservation

Reviving Pig Kidneys Following Extended Freezing

According to НВ — Техно: Scientists have successfully restored the function of pig kidneys after they were frozen for months, with one organ preserved for over a year, by using a vitrification technique enhanced with iron oxide nanoparticles. These findings, shared as a preprint on bioRxiv, are currently undergoing peer review.

The organs were stored in cryogenic conditions before being carefully thawed and transplanted back into test pigs. Remarkably, the kidneys regained their natural coloration and resumed urine production. Vitrification involves cooling tissues to around -150 °C, turning them into a glass-like state that prevents ice crystal formation. Incorporating iron oxide nanoparticles into the cryoprotectant solution improved heat and electrical conductivity, helping maintain organ stability at -120 °C for extended durations, potentially indefinitely.

Implications for Organ Transplantation

Earlier, the research team demonstrated successful transplants of thawed kidneys in rats in 2023 and pigs after 10 days of freezing in 2025. In the United States, more than 100,000 people currently await kidney transplants. While hearts and lungs must be transplanted within about 6 hours, kidneys have a longer window of up to 36 hours.

Eric Finger, one of the lead researchers, reflected: 'A decade ago, I wouldn’t have been very optimistic that this would actually work.'

Following the latest transplant, he added, 'This is a major breakthrough.'

Despite these encouraging results, the team highlights challenges that remain for scaling up organ vitrification, including:

• Efficient and safe warming procedures
• Maintaining cryoprotectant stability
• Logistics of transporting preserved organs
• Addressing biological toxicity concerns

This advancement holds significant promise for transplantation medicine, as improving long-term organ preservation could dramatically reduce donor shortages. Given the thousands awaiting kidney transplants worldwide, technologies that extend organ viability may be crucial in increasing successful transplant outcomes. Ongoing research in this area could redefine preservation standards and transform the future of transplant surgery.