Supercooled pig kidneys have been stored outside the body for days and then reimplanted into pigs, MIT Technology Review reported, a result that points at one of transplant medicine’s blunt constraints: donor organs do not stay usable for long once removed, even when packed on ice.
The work came from Matthew Powell Palm of Texas A&M and colleagues. According to MIT Technology Review, the team held pig kidneys at −4 °C, or 25 °F, without using cryoprotectant chemicals, then successfully transplanted the organs back into pigs. Powell Palm said those kidneys performed better than kidneys kept on ice.
That is a practical target, not just a lab flex. Donor organs usually have only hours outside the body, which makes matching, testing and transport a race with bad margins. Longer preservation could give doctors more time to assess an organ, find a better recipient match and move it farther without watching the transplant window collapse.
Can organs be preserved outside the body for days?
Some organs can now be kept viable longer than traditional ice storage, but the field is still far from routine organ banking. The pig kidney work shows days-long supercooled storage in an animal model, while machine perfusion systems can keep some livers and kidneys going for up to about 24 hours.
The pig result matters because pigs have organs similar in size to human organs. That makes them useful for testing preservation methods that might one day be relevant to human transplantation, though MIT Technology Review did not report that the method has been used for human organ transplants.
Freezing a whole organ remains the ugly part. Ice crystals tear through tissue and can make an organ unusable. Cryopreservation tries to avoid that by cooling cells so rapidly that they enter a glasslike state rather than forming ordinary ice.
That approach is routine for eggs, sperm and embryos. MIT Technology Review reported that embryos can be cooled to −196 °C in less than two seconds and still be used after decades in storage. Whole organs are a different problem. No human organ has been successfully cryopreserved, thawed and transplanted, according to the report.
Cryonics sits at the far speculative end of the same temperature problem. MIT Technology Review previously reported on Stephen L. Coles, a gerontologist who chose to have his brain cryopreserved after his death in 2014. His body was taken to Alcor in Arizona, where staff removed his head, perfused the brain with cryoprotective chemicals, removed the brain from the skull and cooled it to −146 °C.
Years later, cryobiologist Greg Fahy studied pieces of Coles’s brain and found that cells that had shrunk “bounced back” after rewarming, MIT Technology Review reported. That did not show the cells were alive, and it did not show that reanimation would be possible. Powell Palm put the uncertainty more bluntly: “There are so many ways those neurons could be toast.”
Researchers are also attacking the time limit with machines rather than colder storage. Perfusion devices pump nutrients through organs, copying part of what blood flow does in the body. MIT Technology Review said these systems have become more common over the past decade and are usually used to preserve livers and kidneys for up to about a day.
The same idea is spreading beyond the usual transplant organs. Researchers are adapting perfusion systems for eyeballs, a step that could support whole-eye transplant research. Scientists in Valencia also built a uterus perfusion system nicknamed “Mother” and used it to keep a human uterus alive outside the body for a day, according to MIT Technology Review.
The direction is clear enough: colder storage, perfusion machines and chemical protection are all attempts to buy time. The hard part is buying that time without turning a transplantable organ into a beautiful, useless block of biology.
This story draws on original reporting from MIT Technology Review.
