Alcor: mouse brain slices recover up to 80% of metabolic activity 4 to 5 days after rewarming, and a modified M22 cryoprotectant solution now penetrates deeper into a whole pig kidney
Alcor: mouse brain slices recover up to 80% of metabolic activity 4 to 5 days after rewarming, and a modified M22 cryoprotectant solution now penetrates deeper into a whole pig kidney
At Alcor’s internal strategy meeting in 2026, research director Nick Llewellyn and bioengineer Wonjin Cho described two laboratory projects. The organization posted the recording on YouTube on September 16. Their preliminary data suggest that mouse brain slices retain up to 80% of metabolic activity four to five days after rewarming, and that a modified M22 solution now penetrates deeper into a whole pig kidney. Both results were presented at Cryo 2026.
Cryopreservation research faces two bottlenecks that Alcor’s laboratory is investigating: how long tissue remains alive and functional after rewarming, and whether vitrification can scale from laboratory animal organs to a human-sized organ.
Cho is developing an organotypic mouse brain slice culture model that uses tissue slices 300 microns thick to compare cryoprotectant solutions directly. The slices are vitrified in liquid nitrogen, rewarmed, and kept in an incubator for a week while their structural integrity and metabolic activity are monitored. Llewellyn reported the initial figures:
We have very good preliminary data: we can recover up to 80% of metabolic activity and tissue viability even after four to five days. There is still a lot of work to do on this project.
A similar experiment has already been reported in a peer-reviewed paper in PNAS: adult mouse hippocampal slices recovered metabolic and synaptic electrical activity after vitrification.
The second project addresses scale. In January 2026, Alcor tested pig kidney vitrification: 40% of samples showed excellent results, while 60% developed ice crystals in the medulla, the hardest part of the kidney to reach. In May, the organization released a laboratory video with no details of the protocol or solution. The September video is the first to identify the solution as modified M22 and report a preliminary result from testing it.
We were able to modify the M22 formulation so that it now penetrates the kidney much better. I think we are very close to publishing this work. Several very good scientists outside Alcor have encouraged us to publish it.
Cryobiologist Gregory Fahy and his team at 21st Century Medicine developed M22. In the 2000s, they used it to achieve a result that remains unsurpassed: a rabbit kidney sustained the animal’s life after vitrification, rewarming, and transplantation. A pig kidney is comparable in size to a human kidney, so moving from rabbit to pig kidneys brings the work closer to the scale of the human body.
Llewellyn said that papers on the vitrification of rat and rabbit organs had persuaded him to enter cryobiology and propose that Alcor undertake scientific research. That was how he came to lead the organization’s research department.
Both results were presented at Cryo 2026, the annual meeting of the Society for Cryobiology, a scientific society founded in 1964. This year’s meeting took place in Seattle in mid-July. According to Llewellyn, other cryobiologists received the work well.
Both bottlenecks, long-term tissue survival and the size of the organ being vitrified, remain unresolved. The work now provides a specific numerical result for tissue survival and a concrete technical advance toward vitrifying larger organs.