# Enhanced supercooling for extending non-freezing preservation in preclinical porcine and human donor livers

> **NIH NIH R44** · SYLVATICA BIOTECH, INC. · 2024 · $965,379

## Abstract

ABSTRACT. One in five liver patients on the transplant waitlist die before a new liver is found, while many more
patients are never listed but could benefit from liver replacement. While “bridge-to-transplant” technologies
(ventricular assist devices, dialysis) have transformed the outlook for heart and kidney failure, no such treatment
exists for patients with liver failure. Current liver sharing limits (about 500 miles) are based on short preservation
durations (6-10 hours). Extending preservation to a few days would enable nationwide donor-recipient matching,
allowing many livers that are not transplanted today (e.g., subsets of extended criteria donor livers have been
shown to offer substantial survival benefits) to be offered to the patients who most need them. Current standard
practice involves the vascular flush of livers with cold storage solution and subsequent transport on ice, to
maintain viability via hypothermic static storage. While research has shown that lower temperatures are needed
for viable, extended storage durations, storage of organs at or below 0°C risks ice formation (and significant
damage) within the organ. However, it is possible to supercool water-based solutions beyond 0°C while
remaining liquid in a metastable state. Published work from our group has shown that supercooling livers below
0°C can yield several fold increases in cold storage time. For example, simple supercooling has achieved 100%
survival after three days with storage at -6°C in a rat transplant model. While our group has also supercooled
and stored human livers at -4°C for a cumulative 27 hours, a significant improvement over current limitations in
cold ischemic storage (6-10 hours), further extending the storage duration or decreasing the storage temperature
pose additional challenges at this scale. The metastable nature of supercooled solutions can still result in
stochastic ice nucleation and damaging crystal growth, a risk which scales with increasing organ size. The
innovation here embodies development of novel techniques for a “next generation”, non-frozen preservation
paradigm, dubbed “Enhanced Supercooling”. This will enable practically stable ice-free storage of clinical-size
livers (pig and human) at high subzero temperatures (effective in nature but not yet studied extensively for human
organ preservation). For this direct to Phase 2 proposal, building on our successful Phase 1 equivalent work, in
partnership with Harvard/MGH and Johns Hopkins Univ, we develop methods for Enhanced Supercooling of
human size livers via: 1) exploration of strategies for longer duration, lower temperature supercooling via (i) air-
liquid interface sealing with immiscible oil, (ii) biocompatible synthetic ice modulators to inhibit heterogeneous
ice nucleation; 2) enhancement of subzero cooling for ice-free preservation by freezing point depression (FPD)
guided stable near equilibrium non-frozen storage, with biocompatible cryoprotective agents; 3) optimization...

## Key facts

- **NIH application ID:** 11008882
- **Project number:** 1R44DK136457-01A1
- **Recipient organization:** SYLVATICA BIOTECH, INC.
- **Principal Investigator:** Simona C Baicu
- **Activity code:** R44 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2024
- **Award amount:** $965,379
- **Award type:** 1
- **Project period:** 2024-09-17 → 2027-06-30

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/11008882

## Citation

> US National Institutes of Health, RePORTER application 11008882, Enhanced supercooling for extending non-freezing preservation in preclinical porcine and human donor livers (1R44DK136457-01A1). Retrieved via AI Analytics 2026-05-27 from https://api.ai-analytics.org/grant/nih/11008882. Licensed CC0.

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