EverLife Capital · November 9, 2026
The quick question: how long can a donor heart last outside the body before it must be transplanted? The answer: about 4 to 6 hours, on standard cold storage.
Why The Clock Matters
On standard cold storage, donor hearts are typically transplanted within about 4 to 6 hours of removal. Federal transplant guidance says lungs are usually transplanted within 6 hours, livers within 12 and kidneys within 36. Machines that pump fluid through an organ can buy more time: in a Zurich case reported in 2022, a damaged human liver was kept on a machine for three days, then transplanted. Transport matters too. A KFF Health News and Reveal investigation of voluntarily reported shipping data found nearly 170 donated organs could not be used between 2014 and 2019 because of transport problems. Freezing and banking organs could give transplant teams far more time.
The Startup Trying To Pause Biological Time
Until Labs (formerly Cradle), founded by Laura Deming and Hunter Davis, announced a $58 million Series A led by Founders Fund in September 2025 and says it has raised more than $100 million to date.
Shown so far: electrical activity returning in rewarmed slices of rodent brain tissue. The company says it has scaled to testing protocols in large-animal organs. It has not reported a whole-organ transplant.
Next: organ banking for transplant patients first. Reversible whole-body preservation comes later on its roadmap, in animals first.
No human transplant results publicly reported. Private company, no public shares.
Rewarming Is The Hard Part
Freezing an organ is only half the problem. Warming it back up fast and evenly, without cracks or ice damage, is the other half. Researchers at the University of Minnesota add tiny iron oxide particles to the organ’s protective solution, then use a magnetic field to heat the particles so the organ warms from the inside. In rats, kidneys stored and rewarmed this way kept the animals alive for the full 30-day study, after storage of up to 100 days.
A small South Carolina company, Expanse Bio, received a National Institutes of Health research award of about $2 million in 2024 to study this kind of rewarming for preserving kidneys for babies and young children. That is research funding, not evidence it works in children. Private company.
The Company That Has Already Preserved 28 People
Tomorrow Bio, based in Berlin, is a cryonics provider. Preservation starts only after a member is legally declared dead: a standby team begins cooling right away and replaces body fluids with a protective solution. The body is stored in liquid nitrogen at minus 196°C in Switzerland. As of August 2026 it reported 28 people in storage, 14 pets and more than 1,000 full members. In 2025 it said it planned to expand into the US.
The honest caveat: no human has ever been revived from whole-body cryopreservation. Private company.
Real Or Hype?
Freezing and banking organs: real science, still early. In the studies we reviewed, frozen and rewarmed organs have been tested in animals, not yet in human patients.
Reviving a frozen person: not shown. Treat it as a long-shot bet, not a treatment.
What This Means For Your Healthy Years
Organ banking would not slow aging itself. Its biggest effect would be for people waiting on a transplant: more donated organs used and less racing against the clock. One thing you can do today is register as an organ donor in your state or country.
How To Tell If A Company Like This Is Real
The first question I ask: what has it actually shown, and in what? Tissue slices, rats, pigs and people are very different levels of proof. Until Labs has shown tissue results and says it is testing protocols in large-animal organs, but it has not reported a whole-organ transplant or any human results. That doesn’t make it a bad company. It tells you how early it is.
Want The Full Picture? Join The Early-Bird List (50% Off)
I’m writing a deep dive: “Freezing Time: The Companies Trying To Pause Biological Time.”
Every serious company in freezing and organ banking, public and private
What each has actually shown, and in what: tissue, rats, pigs or people
Funding, next milestones and red flags
My research classification for each one: Watch List, Scout or pass
Early-bird price: $24.50. Planned regular price: $49. No payment today.
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Know someone waiting on a transplant, or curious about this? Forward them this page.
Sources: HRSA organ donation guidance (preservation times); Nature Biotechnology, 2022 (three-day liver perfusion); KFF Health News and Reveal investigation of voluntarily reported UNOS shipping data (organs lost in transit); Longevity.Technology, Sept 23, 2025 (Until Labs); Until Labs blog, 2025 to 2026; Tomorrow Bio stats page, August 2026; Nature Communications, 2023 (kidney vitrification and nanowarming in rats); SBIR.gov (Expanse Bio awards)
EverLife Capital publishes general educational research, not personalized investment or medical advice, and nothing here is a recommendation to buy or sell any security. The companies mentioned are private. EverLife Capital sells the report described on this page and the EverLife Capital membership. No company covered paid for coverage, directly or indirectly. Early research and animal results may not lead to treatments for people. EverLife Capital is published by Consult US, LLC. Neither Eric Pemper nor Consult US, LLC holds positions in companies mentioned. Some research and summaries are prepared with AI assistance and reviewed before publication.
