New freezing method slashes thaw time for emergency blood transfusions

A transformative new method for freezing human red blood cells has been developed by researchers from the Universities of Manchester and Leeds.

The technique, created with industry partners CryoLogyx, has the potential to revolutionize how blood is stored and delivered in emergencies, remote locations, and military operations.

Led by Dr. Fraser Macrae from Leeds and Professor Matthew Gibson from Manchester, the research is published in the Cryobiology journal.

Rather than using traditional cryoprotective agents—substances which protect cells by preventing ice, the team developed a cocktail which includes a new class of macromolecule which protects cells by preventing damaging ice from forming inside them, known as polyampholytes.

Beating the clock: Delivering on-demand blood

Red blood cell transfusions are critical for treating trauma, anemia, and complications from chemotherapy or surgery. However, refrigerated red blood cells have a shelf life of just 42 days, creating logistical challenges for maintaining a reliable blood supply—especially in crisis situations or remote regions.

To allow blood to be banked for future use, cryopreservation (freezing) is an essential technology. Currently, glycerol is used as a cryoprotectant—a substance which protects the blood from cold stress by preventing ice from forming within the cells. However, it comes with a major drawback: a laborious and time-consuming thawing and washing process that can take over an hour per unit of blood. This delay can be life-threatening in emergencies and complicates its use in, for example, crisis or military situations.

The new method reported today, addresses this washing speed problem. By combining three cryoprotectants—polyampholytes (a type of polymer), DMSO (a cryoprotectant typically used for stem cells), and trehalose (a sugar)—the researchers have developed a formulation (PaDT) that not only preserves red blood cells effectively but also reduces the post-thaw washout time by over 50 minutes compared to glycerol.

“Our goal was to create a system that allows blood to be frozen and then used almost on demand, with PaDT, we’ve achieved that. It’s faster, simpler, and results in better recovery of healthy, functional red blood cells,” says Dr. Fraser Macrae, University of Leeds.

How it works

The PaDT formulation leverages the unique properties of its three components:

Polyampholytes: unique polymeric cryoprotectants which have many beneficial properties including preventing ice forming inside cells.
DMSO: a permeating cryoprotectant that enters cells quickly replacing water molecules, stopping ice from forming
Trehalose: a sugar found in extremophiles like tardigrades; trehalose protects cells from dehydration and stabilizes proteins and membranes.

Together, these agents work to protect RBCs during freezing and allow for a simplified, low toxicity thawing process.

This breakthrough has the potential to transform emergency medicine. With this new method, frozen blood could be stockpiled and rapidly deployed in disaster zones, on the battlefield, or in rural hospitals—without the need for constant donations or complex equipment.

“Imagine a future where blood can be ‘on tap’, ready to transfuse asap to those who need it most. This technology brings us one step closer to that reality,” says Professor Matthew Gibson, Manchester Institute of Biotechnology, The University of Manchester.

The research team is now exploring how this method can be integrated into automated systems for large-scale blood processing. They are also investigating its potential for preserving other cell types, including stem cells and platelets.