Antifreeze proteins from fish living in icy seas have inspired a new way to freeze blood for safe storage.
Researchers say polyvinyl alcohol, a common polymer, mimics antifreeze properties found in fish like arctic cod, allowing blood cells to better survive storage at freezing temperatures. It works by inhibiting the growth of ice crystals during thawing—which would otherwise damage the blood cells and make them unusable in medical settings.
Currently in the UK, blood is stored by refrigeration, but it can only be kept this way for up to one month, so hospitals are dependent on a constant supply of donors to keep blood banks topped up.
Many other donor cells also need to be cryopreserved, including bone marrow for leukemia patients. The need for new technologies is expected to grow in importance with the growth of biobanks and the emergence of more stem cell therapies, researchers say.
Some countries, including the United States, already use blood cryopreservation, but the current method requires the addition of large quantities of organic solvent. Every liter of blood requires up to a liter of solvent to prevent the formation and growth of ice crystals, which can kill the cells.
Blood’s shelf life
The organic solvent still has to be removed before the blood is used in a process and that can take several days.
The new system of freezing requires an additive of only 0.1 percent of the volume of the blood and it doesn’t need to be removed once the blood is defrosted, so can be put to use rapidly.
Scientists believe the discovery offers a broad range of possible applications, from in vitro scientific research through to stem cell therapies in the clinic.
“We know that certain types of fish survive perfectly well in sub-zero sea temperatures without their blood freezing,” says Matthew Gibson from the department of chemistry at the University of Warwick. “We used this as a starting point to search for synthetic substances which reflect what nature already does so well.
“On closer examination it turns out that polyvinyl alcohol, which is actually a derivative of wood glue, mimics the properties of the antifreeze proteins found in these kinds of fish.”
Polyvinyl alcohol has three things in its favor when applied to freezing blood, Gibson says.
“Firstly, it reduces the growth of ice crystals during thawing, secondly it reduces the need for organic solvents, and crucially, it reduces the time between defrosting and having transfusion-ready blood by eliminating the need to remove solvent.
“Although we still need to run further tests, this new method looks very promising in terms of vastly extending the shelf life of blood stored for medical procedures and therefore preventing dangerous dips in blood availability at certain times of the year.
“In addition to these benefits for blood we are excited by the scope for other applications including cell-based therapeutics for patients with rare and serious diseases including certain cancers and neurological conditions.”
The Royal Society and the Science City Research Alliance supported the research. The findings are published in the journal Nature Communications.
Source: University of Warwick