Problem Statement and Roadmap

We’re building a pause button for biology: a technology which halts molecular motion across long timescales and restarts it on demand. We will use this to help patients in two time-sensitive areas of medicine.

Organ Donation

Thousands of organs are rejected every year due to the short viability window immediately following the organ’s excision from the donor. Pausing molecular motion in donor organs after excision would remove biologically-imposed time constraints on testing and matching procedures, increasing the available pool of life-saving organs and reducing rejection rates among recipients.

Medical Hibernation

Despite the ever-increasing frequency of medical breakthroughs, many patients won't live to see a cure to their disease. By reversibly pausing the biological function of a patient, we can extend the critical window of care for those without other treatment options. For example, in the decade between the onset of the AIDs epidemic/pandemic and the widespread availability of combination antiretroviral therapies, more than four million afflicted patients died (source UNAIDS (2023)). In 1950, a patient with cystic fibrosis would have died in infancy, while those born today with the condition have a life expectancy that often extends into middle age. Finally, patients today still regularly die of cancers that could have proven treatable were they afforded the innovations provided by a few more years of rigorous medical research. Medical hibernation technology could help these patients pause their biological time and access cures that are right around the corner.

The Core Technical Challenge

The solutions to both challenges share a simple insight: the rate of molecular motion and chemical reactions can be controlled with a single knob — temperature. Cooling a patient to deep hypothermic temperature (below 20°C) is a common strategy for protection from ischemic damage during cardiac surgery ^[1] . Donor are transported in coolers to extend their viability window. Embryos for in vitro fertilization (IVF) can be stored for decades before implantation by cooling to cryogenic temperatures (below -130°C), where the viscosity of water dramatically increases and all molecular motion stops ^[2]. This phase transition from liquid to glass is known as vitrification. In this state, molecular motion is too slow for water molecules to rearrange into damaging ice crystals. Over one hundred thousand babies are born each year from cryopreserved embryos or eggs stored using this strategy ^[3].

Scaling cryopreservation technology from embryo-sized samples to tissues, donor organs, or whole patients requires cooling and rewarming rates that are both fast enough to prevent ice formation between 0°C and -130°C and gentle enough to avoid fracture from thermal gradients. Ice crystals nucleate at a very high rate in water cooled below -20°C (up to 10^23 cc-1 s-1)^[4], so without any chemical modifications, tissue cannot be cooled at a rate that will outrun this process. Fortunately, perfusing an organ or organism with molecular cryoprotective agents (CPAs) while held at hypothermic temperatures before cryopreservation can dramatically reduce ice nucleation and extension rates during the cooling phase.

Achieving the right combination of CPAs, engineering systems, and surgical protocols is a considerable challenge, but recent findings show strong proof-of-concept. In 2023, a study from the University of Minnesota demonstrated reversible preservation of a whole rat kidney, significantly derisking cryopreservation as a viable preservation strategy for donor organs ^[5]. In 2024, we preserved electrical activity in an acute slice of rat brain tissue, a first milestone for both our research tissue and whole patient objectives [whitepaper]. This year, we’re scaling our technology to preserve preclinical models of human organs.

Roadmap

There’s a long road ahead to achieving our research goals, but we view the following as the key steps to bring cryopreserved donor organs to the clinic and derisk whole-body reversible cryopreservation:

• Recovery of electrical activity from cryopreserved and rewarmed acutely resected rodent neural tissue. [complete! see whitepaper]

• 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

Each of these milestones will require advances across multiple scientific and engineering disciplines. Below, we’ve curated a short representative list of the problem domains and their corresponding technical approaches.

Molecular Discovery

Cryoprotective agents are at the core of the cryopreservation process. To maximize the viability of biological systems through the preservation process, our molecular development group screens novel compounds and formulations for improved efficacy, biocompatibility, and biodistribution. Programs include:

• Enhanced cryoprotectant efficacy – Using a combination of computational and experimental screening, we design next-generation cryoprotectant formulations that prevent ice formation at lower concentrations than the current state of the art.

• Biocompatible cryoprotectants – Most cryoprotectants are toxic to delicate tissue. Using a combination of cultured cells and more translational screens, we optimize our CPAs to be well-tolerated at the concentrations at which they are effective ice inhibitors.

• Enhanced Biodistribution – Organs and organisms can be perfusively loaded with cryoprotectants using the native vasculature for mass transport. Unfortunately, the endothelial layer in organs slows the diffusion of perfused cryoprotectant molecules out of the vasculature into the volume of the tissue. We engineer our formulations to minimize the required loading time by facilitating diffusion of CPAs from the vasculature to the tissue volume.

Surgical Protocols

Preparing organs and whole organisms for cryopreservation requires robust vascular access and tight perfusion control. Programs include:

• Organ Perfusion Protocols — To improve experimental depth and throughput, we design hardware and protocols for cannulation, perfusion, and monitoring of isolated preclinical model organs.

• Transplant Model Surgery — We’re developing new protocols with leading surgical teams to maximize translational value.

• Microsurgery Protocols — We’re optimizing surgeries for the cannulation, perfusion, and monitoring of whole rodents presents a particular set of constraints due to their small vascular diameter.

Engineering Systems

• Volumetric Rewarming — Ice forms faster during warming than during cooling, placing stringent requirements on warming rates. As we scale from small tissue samples to whole organs, warming power needs to be well distributed throughout the volume of the organ to prevent thermal gradients in the tissue.

• High throughput screening systems — We leverage cell and tissue-based screening platforms that can scan the combinatorial sample space of cryoprotectant solutions.

• Material Physics Instrumentation and Modeling — We’re building new models and instruments to dig deeper into the physical principles behind ice formation and vitrification.

Citations