New cryopreservation agents allow longer organ storage

Leaps and bounds in the development of cryopreservation technology have allowed rapid advancements in reproductive technology, stem cell therapies, and even to save species from extinction. However, as part of the cryopreservation process, agents are added to protect the cells against damage and dehydration while going through the freezing process.

The two primary agents that have been used in cryopreservation for the past few decades are dimethyl sulfoxide and glycerol, which are both toxic. These agents are also unsuitable for hundreds of cell types, and so far organ and tissue preservation has not been achieved.

Because of this, as many as 60% of donated hearts and lungs are being discarded.

“We have these massive organ shortages, yet most of them just get thrown away” says lead researcher Dr Saffron Bryant from RMIT. “We only have hours to get an organ from a donor to a recipient.”

A new body of research has trialled the effectiveness of deep eutectic solvents as cryoprotectants. The team compared six different solvents’ suitability for mammalian cells, and tested for thermal properties, toxicity, and permeability into four types of mammal cells including skin and brain.

They identified that a deep eutectic solvent made from proline and glycerol was the most effective cryoprotective agent for mammal cells. This solvent was also less toxic than when using its components individually, which highlights the potential in optimizing cryopreservation using combination agents. These cryoprotective agents could even be tailored to specific cell types, with potentially thousands of combinations to be developed.

The team were also able to extend the incubation time of the cells with this new cryopreservation agent.

“Incubating these cells with the cryoprotectant at 37°C for several hours prior to freezing and keeping them viable is a crucial step towards the storage of organs and tissues,” says Bryant. “It means we could expose organs to the cryoprotectants for long enough for them to penetrate into the deepest layers of the organ without causing damage.”

With about 1,850 people on the organ transplant waiting list in Australia, and more than 100,000 waiting for a transplant in the US, these new cryoprotective agents could potentially help keep donated organs viable for years, rather than hours.

“We have a long way to go with our research, as we’ve only looked at single cells and it’s a much more complicated process for organs,” says Bryant. “But if we can develop this approach to store organs, we could eliminate organ shortages – there would be no waiting lists at all.”

To find out more, this original research has been published in Journal of Materials Chemistry B.

Microscope image of neural cells after freezing with the team’s new cryoprotectant. The cells have been stained with fluorescent dyes. Credit: Saffron Bryant

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