Why Cryopreservation is No Longer Science Fiction with Until Co-founder and CEO Laura Deming
What if we could pause biological time to wait for a cure for a disease? Thanks to innovations and research in reversible cryopreservation, this possibility is no longer just science fiction. Sarah Guo sits down with Laura Deming, CEO and co-founder of biotech startup Until, to dive deep into the growing field of reversible cryopreservation. Laura talks about how her time as a Thiel Fellow as well as her founding of the Longevity Fund fueled her obsession with solving the “social blindspot” of a ✦ AI generated
Laura Deming establishes that reversible cryopreservation is already proven at small scales — human embryos have been vitrified for 30 years and revived — so the core problem is not feasibility but scaling to organs and whole bodies.
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Laura Deming: We already reversibly cryopreserved tissue, including human tissue, all the time. And we do it for very long time periods. There are kids who were literally cryopreserved for 30 years as tiny embryos. And so the main question is not, is this possible to do at all, it's is it possible to scale up?
Laura describes Until's mission as enabling 'medical hibernation' — pausing a patient's biological time so they can survive until a critical cure emerges. The near-term product is reversibly cryopreserving human organs to solve the transplant logistics problem, where organs routinely expire during transit and patients miss life-saving windows by months.
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Laura Deming: I would think about our goal as trying to create a new form of critical care. The example that I would give that is sort of the core of the company is there's some years where certain diseases such as like metastatic melanoma go from being, like, sort of in a single year, like metastatic melanoma went from being something that you had like a six to nine month prognosis, like less than a year of expected survival, to with new combination immunotherapies, you might have a decade plus of expected survival, or 50% of people sort of surviving over a decade, without getting sort of death from melanoma. The tagline is like, single years can make the difference between a patient dying of terminal illness and like living long enough to make the critical cure. But right now, there's no way to press pause on their biological time. It's like, what if you had an ambulance to the future, right? Like, what if you could take someone who is on their deathbed and find some way to just sort of hibernate them basically until the sort of critical cure for the disease comes online. ... Our long-term goal is reversible whole body cryopreservation for medical sort of hibernation. But in the near term, what we work on is reversibly cryopreserving single human organs to help transplant patients get organs more efficiently.
Ice forms through random nucleation and extension, not deterministically. By spending minimal time in the ice-nucleation temperature range and by tuning cryoprotectant concentration, you can avoid ice damage. Faster cooling and rewarming allows lower CPA concentration, creating a trade-off between engineering and biology.
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Laura Deming: Ice formation is a stochastic process. So if ice just formed unilaterally in any given material past a certain point of temperature, like, you know, just like go from zero to 1, it's like 100% ice, like that might be kind of hard to think carefully about technically, but ice sort of forms through a process of random nucleation and then extension. And this is cool because you can modulate the sort of nucleation, the rate of nucleation and extension to then modulate the probability of ice formation. And because it's probabilistic, if you can do that well enough and you can sort of spend minimal time in the temperature range where ice can nucleate, then that gives you a shot at sort of preventing a lot of ice formation. ... Water expands when it forms ice. That's just hard for your tissue to take without substantial damage. ... The cool thing is that there's sort of a temperature below which ice formation stops happening. So basically, if you can traverse, let's say, you know, going below 0 degrees or less, through to around minus 130, and you can get below that without ice formation, then you're good.
Laura explains that temperature is a rare 'conceptual lever' in biology — it connects molecular motion to a single measurable parameter, and tuning it effectively controls the passage of time at the nanoscale. This allows applying theoretical physics toolkits to cryopreservation in ways that aren't possible for most other biological problems, creating a powerful engineering-biology trade-off.
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Laura Deming: Temperature is such a beautiful conceptual tool, right? It's like temperature as an idea, something that in physics took physicists hundreds of years to come up with. It links like molecular motion to a high, like a single high level measurable parameter. And just tuning temperature like sort of tells you about almost like the relative passage of time of like molecules at the nanoscale. Like that's a highly non-trivial sort of conceptual lever to have on a problem. And in biology, one of the biggest problems is like, it's really hard to find powerful conceptual levers on sort of like for like nanoscale, for manipulating like the nanoscale, that have anything approaching that degree of sort of leverage. Basically, what that gives you is like, you can apply a lot of theoretical sort of, a lot of theoretical toolkit used in physics to model parts of this question in ways that are actually useful. And it is just not true that you can use like equations from physics to think usefully about almost any other problem in biology.
While the roadmap for whole-body cryopreservation is clearer than Laura initially expected, the brain remains the critical unknown. It is unclear what kind of injury the brain can sustain during a preservation protocol and what level of functional fidelity is possible to restore.
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Laura Deming: The big unknown to get to whole body reversible is the brain. It's unclear, like the brain can withstand a lot of change and does withstand a lot of different types of damage or change with age, for example. But it's unclear whether, like what kind of injury the brain could sustain in the context of like a whole body reversible preservation protocol and then like what level of fidelity it's possible to do.
Laura explains that the organ preservation product is not just a business milestone — it's an existential test for the company. If they cannot solve the logistics of organ preservation (which is a clearly defined, near-term problem), they have no credibility to pursue whole-body cryopreservation. This gives the team a concrete, urgent goal that directly validates their long-term vision.
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Laura Deming: I think it helps to have a very concrete goal that clearly is relevant to our long-term goal, right? I think another thing that was inspired us about that product was like, if we're at all talking about whole-body reversible cryopreservation, and we can't make a dent on that problem. There's no version of it not going through it. It's like, if you're serious, that should be doable. And if you can't do that, then you're not the company to do the long-term thing. So it was nice for us to have a very clear benchmark for ourselves of, are we correct that this is a tractable technology on that scale?