The quest to keep organs alive outside the body

Researchers are pioneering new methods to preserve human organs outside the body for longer periods, aiming to overcome a critical bottleneck in transplantation: the short survival time of donor organs. The field is exploring techniques ranging from supercooling without ice formation to machine perfusion and cryopreservation, with recent successes in animal models offering hope for future organ banks.

Key takeaways

• A research team successfully supercooled and stored pig kidneys at -4°C for days before successfully reimplanting them, a landmark achievement.
• Machine perfusion devices, which mimic the body by pumping nutrients through organs, are now commonly used to preserve livers and kidneys for about 24 hours and are being adapted for other organs like uteruses and eyeballs.
• Cryopreservation, which rapidly cools cells to a glasslike state, is routine for eggs and embryos but has not yet been achieved for whole human organs, though some opt to preserve brains or bodies in the hope of future revival.
• The overarching goal is to create organ banks, allowing for better matching, testing, and transportation of organs to address the severe donor shortage.

Advances in supercooling and perfusion

The latest breakthrough comes from researchers who supercooled pig kidneys to -4°C (25°F) and preserved them for days before successfully transplanting them back into pigs. This approach, led by Matthew Powell Palm and colleagues, did not require cryoprotectant chemicals and resulted in better outcomes than traditional ice storage. Separately, machine perfusion technology has become a standard tool, extending the viable storage time for organs like livers and kidneys to around 24 hours. Scientists are now expanding its use, with one team in Valencia developing a device nicknamed “Mother” that kept a human uterus alive for a full day, and others exploring its application for whole-eye transplants.

The cryopreservation frontier

While supercooling and perfusion offer near-term solutions, the field of cryopreservation aims for much longer storage. This technique involves ultra-rapid cooling to -196°C to prevent ice crystal formation, which is destructive to cells. It is currently used to preserve eggs, sperm, and embryos for decades, but scaling it to whole human organs remains an unsolved challenge. Some individuals, like gerontologist Stephen L. Coles, have chosen to have their brains cryopreserved post-mortem. A later examination found his brain cells shrank and then “bounced back” upon rewarming, though experts caution this does not equate to viability and significant cellular damage likely remains.

Why it matters

The ability to preserve organs for extended periods outside the body could revolutionize transplant medicine. A primary reason for the dire shortage of donor organs is their extremely limited shelf life—often just hours on ice. Creating organ banks would allow doctors to meticulously match donors with recipients, conduct necessary safety tests, and transport organs across long distances without the current frantic race against time. Each advancement in supercooling, perfusion, or cryopreservation brings this vision closer to reality, potentially saving countless lives on transplant waiting lists.