Until Labs

Source: Bloomberg

Founded by Laura Deming (CEO) and Hunter Davis (CSO), Until Labs first began as a company called Cradle Healthcare, a startup that emerged out of stealth in mid-2024 with $48M in seed funding. Prior to then, the company had been operating in stealth with the mission of creating a “pause button for biology”. The company would later raise a $58M Series A led by Founders Fund.

To say Deming is a unique individual would be an understatement. Growing up in New Zealand, Deming developed an early fascination with aging. At age 8, she became captivated by the idea that lifespan might be malleable; by 12, she had persuaded her family to relocate so she could work in Cynthia Kenyon’s aging research lab at UCSF. She was later admitted to MIT at 14 to study physics, but dropped out to accept a place in the inaugural class of the Thiel Fellowship in 2011. Using the $100k from the fellowship, she started what is known today as The Longevity Fund, one of the world’s first venture capital firms devoted entirely to extending healthy human life. Cryopreservation as a concept had been on Laura’s mind for a number of years, yet something she did not seriously consider pursuing due to the perceived impossibility.

Hunter Davis was meanwhile on an extensive journey through academia. After graduating from the University of Chicago in 2013 with degrees in physics and economics, he moved to Caltech to pursue a PhD. There, in Mikhail Shapiro’s lab, he spent five years exploring the strange intersection of quantum physics and cellular biology, using light and sound to probe the inner workings of life at the molecular level. Upon completing his doctorate, he joined Adam Cohen’s lab at Harvard as a postdoctoral fellow, where he continued to push the boundaries of optical biophysics for nearly four years. Being on track to becoming a professor, it would take the loss of Davis’ father-in-law to terminal lung cancer only months before the approval and roll out of Keytruda (a drug that might’ve saved his father-in-law), as well as a special call from Laura, for him to make a bold trajectory shift towards building a startup.

The fundamental reason why the problem of organ cryopreservation has not yet been cracked is simple: ice formation. Many people don’t realize this, but freezing and ice formation are not the same thing. If ice crystals form in the sample you are trying to preserve, they can wreak havoc on the tissue. It is possible to freeze something without ice crystals forming (in a process called vitrification) and it is already used routinely when women freeze their eggs for IVF.

Vitrification works beautifully for small specimens, say an oocyte or embryo, precisely because the volume is so small that the entire specimen can be cooled extremely rapidly and uniformly (thus preventing ice‐crystal formation). In such cases you can plunge the specimen into liquid nitrogen (-196 °C) and essentially outrun ice nucleation and crystal growth. The water becomes glass-like rather than crystalline, and the cells escape damage from ice formation.

When you scale up to something the size of a human heart, the situation changes. Cooling the outer surface is relatively straightforward, but the interior lags behind. Thermal gradients develop: the surface is freezing, while the core remains warm. If you plunged a heart into liquid nitrogen, you would pull it out fractured, the uneven freezing having torn it apart. It’s simple math: as volume increases, surface-area to volume ratio decreases. If you cannot cool something fast enough (the danger zone is between 0 °C and roughly -100 °C), ice crystals will begin forming in the tissue that sits in that zone.

Even if you were somehow able to cool an entire organ down to -196 °C without any ice forming, you still have to cross the danger zone again when you warm that organ back up. Thus, the cooling phase and the warming phase must both be performed in a way that prevents ice formation.

Of course, last of all, the organ must still function once it is vitrified and devitrified. Brain tissue must still fire off electrical signals. Hearts must still beat.

This is Until Labs’ equivalent of SpaceX’s “landing the rocket” problem. While not physically impossible, it presents a challenging engineering problem indeed.

It’s February 13th, 2024, and the team at Until Labs is spending another evening trying to thaw and recover a vitrified 300μm-wide slice of a resected mouse cerebellum. The team isn’t quite ready for a whole heart yet, but a successful vitrification and rewarming of even a slice of one of the most delicate pieces of biological tissue will prove to be an important milestone indeed.

This slice of brain tissue is seated atop of a multielectrode array, a standard lab tool for determining brain activity via measured action potentials. Moments prior, the tissue was loaded with an in-house CPA compound and vitrified.

The team is trying to see if this thawed brain slice, after being quickly cooled to -196°C, can recover and fire action potentials like a normal brain slice would. The frost-covered, vitrified cerebral slice is suddenly exposed to an alternating magnetic field. Here, magnetic particles adjacent to- or spread throughout- the sample itself oscillate back-and-forth, generating an even distribution of heat throughout the slice. The brain tissue is heated back up to 37°C, and the thawed slice promptly placed on a microelectrode. After countless cycles of freezing and thawing cells to no avail, a spiked pattern appears on the EMG, reading out signals from the neural slice.

a) Cerebral slice morphology post-cryopreservation, b) Thawed cerebral slice channel activity at thawed baseline

Hunter and the rest of team think that the result is an artifact— surely this is just noise. They figure that if the signals came from a real recovered neuron, then it should act like a neuron in the face of a predetermined stress test. The team perfuses a solution containing a mimicking compound of acetylcholine, carbachol, as well as a solution containing the neurotoxin tetrodotoxin. Carbachol is a cholinergic agonist which increases the intracellular Ca2+ gradient, leaving neurons more excitable. Tetrodotoxin on the other hand is a powerful neurotoxin found in pufferfish that causes widespread paralysis by blocking sodium ion channel activity in the nerve cells of the peripheral nervous system.

If this neuronal slice really did recover and was acutely firing, then the introduction of tetrodotoxin would put an abrupt end all of its activity.

The results followed the logical flow after thawing; channel activity rose with carbachol treatment, while tetrodotoxin abruptly halted signaling. This is the exact behavior what would be expected from neurons interfacing with a acetylcholine receptor agonist and a neurotoxin, respectively. These results affirmed the spikes being read out just moments ago— the team had just vitrified and recovered a piece of the brain.

It was a wonderful first step for the fledgling startup, and gave them the ammunition to publicly launch just a few months later.

When Until Labs (at the time still named Cradle Healthcare) was formally announced in June 2024, it arrived onstage with two announcements: news of the recovered mouse brain tissue, along with the following roadmap of technical milestones:

• Recovery of electrical activity from cryopreserved and rewarmed acutely resected rodent neural tissue. (Completed)

• Preclinical validation of donor organ cryopreservation

• Successful human organ cryopreservation first-in-human trial

• Preservation of an entire rodent for 2 hours in a hypothermic state

• Reversible whole-body cryopreservation of an entire rodent

In their original materials published at the time, Until Labs mentioned that it may pursue the banking of neural tissue as a product to be marketed to pharmaceutical companies wishing to have on demand samples for testing novel drugs.

Because access to human brain tissue is so limited, neuroscientists have long relied on rodent neural samples for both basic research and drug development. One of the main barriers has been the ischemic window (the brief period after blood flow stops during which brain tissue remains viable before irreversible damage sets in). Once resected, human brain tissue degrades very quickly, making it nearly impossible to preserve or study at scale.

If human brain tissue could be successfully cryopreserved and stored (which Until Labs showed that it was potentially possible), researchers could one day order viable human neural samples on demand, accelerating neuroscience and improving how faithfully drug development translates from the lab to the clinic.

In the company’s original 2024 problem statement, this was positioned as a flagship application. But following the Series A and rebrand to Until Labs, the updated materials no longer mention it. Future Files speculates that amid weakening pharmaceutical interest in drugs targeting the brain, Until Labs has shelved this for a later date and chosen to focus on organ cryopreservation as their primary profit center as their most recently published materials would suggest. Future Files further speculates that Until Labs has made a major technical breakthrough, as a major Series A round that gives them $58M in fresh capital was likely not raised from nothing. Investors would have had to seen significant technical derisking before plowing more money in, especially given the frigid fundraising environment for biotech at the time of writing this article.

Let us imagine, for a moment, a future where Until Labs has achieved all of its technical goals. Forget the science-fiction dream of cryosleep for now; focus instead on what true organ cryopreservation could unlock.

As mentioned earlier, every donor organ operates on a ticking clock, and that constraint shapes the entire transplant ecosystem. Patients must live within a two-hour radius of their transplant center. Surgeons charter private planes to collect organs in person. Each year, thousands of viable organs are lost to logistical delays or mismatched timing. In 2024, roughly 106,000 people were on the national transplant waitlist, and about 46,000 received organs, according to HRSA. Yet even those numbers understate the need. Many patients with advanced organ failure never make it onto the list at all—excluded by strict eligibility criteria, limited donor availability, or caps on how many candidates each hospital can support.

Now imagine if the clock stopped. If every organ that would otherwise be discarded could instead be vitrified and stored, matching would no longer depend on geography or timing. A patient in New York could receive a heart from San Francisco. Transplants could move from a race against time to a matter of logistics and precision.

According to Grand View Research, the global organ transplant market is currently a ~$15B market, with the US accounting for roughly $3.9B. If we purely look at the market size and its measly estimated CAGR of 9.3%, Until Labs’ future does not look very lucrative.

However, let us take a more bottom-up approach to analyze the opportunity. According to the SRTR, the following number of patients were added to the organ transplant waitlist in 2023 for the United States:

• Kidney: 47,838 new candidates were added.

• Liver: 14,658 new candidates were added.

• Heart: 5,800 new candidates were added.

• Lungs: 3,427 new candidates were added.

The average cost per procedure is as follows:

• Kidney transplant: ~$US 442,500

• Liver transplant: ~$US 878,400

• Heart transplant: ~$US 1,664,800

• Lung transplant: ~$US 929,600

Currently, the organs themselves come as donations, and the cost of the procedures comes from the following:

• Organ acquisition / procurement: Removing the donor organ, preservation, transport, logistics.

• Surgery + hospitalization (“transplant admission”): The actual transplant surgery + the immediate hospital stay (ICU/ward).

• Pre-transplant evaluation + donor/recipient preparation: Workup, diagnostics, donor screening, hospitalization if donor is living.

• Post-transplant care + follow-up: Outpatient visits, imaging, lab tests, readmissions, complications.

• Immunosuppression + maintenance medications: Anti-rejection drugs, monitoring, side-effect management.

• Non‐medical/logistic/indirect costs: Travel, lodging, lost wages for patient/caregiver, organ transport cost beyond hospital billing.

Let’s assume that Until Labs was able to capture 20% of the cost per procedure.

• Kidney transplant: ($442,500 × 20%) × 47,838 annual new patients = $4.23B

• Liver transplant: ($878,400 × 20%) × 14,658 annual new patients = $2.58B

• Heart transplant: ($1,664,800 × 20%) × 5,800 annual new patients = $1.93B

• Lung transplant: ($929,600 × 20%) × 3427 annual new patients = $0.64B

In total, this gives Until Labs a potential $9.38B in potential annual recurring revenue from the US market alone, discounting the fact that those numbers added to the waitlist are understating the real number, given that many patients never even make it to the waitlist given the stringent eligibility criteria. With the advent of an organ bank however, eligibility criteria could be relaxed significantly.

This all assumes of course, that Until Labs can obtain a complete monopoly over the market, so let’s take a look at the competition.

In its public communications, Until Labs positions itself alongside whole-body cryonics organizations such as the Alcor Life Extension Foundation. The company distinguishes itself by emphasizing reversible cryopreservation — the ability to bring tissue back to life intact — which it identifies as the true benchmark for making cryonics viable in the real world.

That said, Until’s real competition likely lies elsewhere. Rather than contending with whole-body preservation outfits, Until competes more directly with the handful of companies working to make organ-level cryopreservation practical for transplantation.

Below are the primary players in this emerging field:

X-Therma — Founded in 2014 by Sofie Wei, Ph.D (CEO) and Mark Kline, Ph.D (CTO) in the San Francisco Bay Area, X-Therma develops ice-inhibiting solutions for organ cryopreservation. The company’s proprietary “peptoid” platform is designed to prevent lethal ice-crystal formation, enabling long-term sub-zero storage while maintaining tissue viability. In March 2024, X-Therma raised an oversubscribed $22.4 M Series B to fund clinical trials and global expansion. While their published data suggest progress toward multi-day organ preservation, they have not yet demonstrated true vitrification.

Sylvatica Biotech — Founded in 2015 by Sebastian Eriksson Giwa, MBA (CEO) and Michael J. Taylor, Ph.D. (CSO), Sylvatica pursued cryopreservation strategies inspired by naturally freeze-tolerant species such as the wood frog. The company’s early work drew attention for its promise, but public updates in recent years have been sparse. Beyond general statements about “potential,” Sylvatica does not appear to have announced any verifiable breakthroughs and may be inactive.

Paragonix Technologies — Founded in 2010 by Lisa Anderson, Ph.D. (CEO), Paragonix builds advanced organ-transport and preservation systems, including temperature-controlled devices like SherpaPak and LUNGguard. While Paragonix plays a role in extending short-term organ viability, it is not engaged in cryopreservation or vitrification research.

In summary, the competitive landscape is remarkably sparse. No company has yet achieved reversible vitrification of a human organ, and only one — X-Therma — appears to be making tangible progress toward multi-day preservation. If Until Labs succeeds, it would unlock indefinite storage of donor organs, a leap far beyond current technologies that merely extend survival from hours to days. Such a breakthrough would not only redefine transplantation logistics but could also grant Until a near-monopoly position in the global organ-preservation market.

Until Labs stands at the edge of one of medicine’s final frontiers: the ability to preserve life itself.

If Until succeeds, organ transplantation would move from an emergency procedure constrained by time and geography to a predictable process of logistics and matching. A heart donated in San Francisco could be stored, shipped, and transplanted in New York weeks (or even years) later. Surgeons would no longer race the clock, and patients would no longer die waiting for a call that comes too late.

Technically, the challenge is immense. Preventing ice formation during both freezing and rewarming requires solving one of the hardest problems in cryobiology. Yet, the company has already shown evidence of progress, demonstrating recovery of neural activity in vitrified brain tissue and attracting over one hundred million dollars in venture funding from top firms like Founders Fund, Lux Capital, and others.

The market opportunity is equally striking. The United States alone sees more than 70,000 new additions to organ waitlists each year, with procedure costs ranging from four hundred thousand dollars for a kidney transplant to more than one and a half million for a heart. The key risk is in Until Labs’ technology, but should they succeed, they will be granted a monopoly position in the global organ-preservation market. Their competition is slim to none.

For now, Until Labs remains an ambitious bet on a simple but world-changing idea: that death from organ failure should no longer be a question of time. If the company delivers on its promise, it will begin to make the organ waitlist a thing of the past, until truly no patient dies waiting.