Flash Freezing Cells Without Antifreeze

By printing minuscule droplets with cells in them, researchers in Japan were able to flash freeze biological samples in the absence of cyroprotectant agents.

AsianScientist (May 15, 2019) – Researchers in Japan have devised a technique to cryopreserve animal cells without antifreeze, or cryoprotectant agent (CPA). Their findings are published in the Proceedings of the National Academy of Sciences.

To keep biological cells or tissue for future use or study, researchers frequently have to freeze them down in liquid nitrogen. Typically, freezing methods require CPA to prevent the formation of large water crystals inside and outside of cells which damage the samples.

In the present study, researchers led by Associate Professor Yoshitake Akiyama at Shinshu University, Japan, were able to freeze the cells quickly enough such that CPA was not required.

“Ultrarapid cooling is much faster than the cooling rate that is typically used in cryopreservation. We call it superflash freezing, and it can almost vitrify and cryopreserve living cells without any CPA,” said Akiyama.

The critical cooling rate required for CPA-free ultrarapid freezing is 10,000 degrees Celsius per second. To achieve this rate of freezing, the researchers used inkjet cell printing technology to deposit cells within droplets each less than 40 picoliters in volume. They demonstrated the feasibility of their technique using mouse cells and rat mesenchymal stem cells, showing comparable performance with cryopreservation methods that require CPA.

In the future, the researchers hope to apply their method to preserve a wider variety of cells, including those that are known to be particularly sensitive to the cryopreservation procedure.

“We plan to use our method to cryopreserve other cells including pluripotent stem cells, whose properties such as stemness and differentiation are known to be susceptible to CPAs. Furthermore, we believe that our method might be suitable for cells such as hemocytes that cannot be stored using a conventional cryopreservation method,” Akiyama added.

The article can be found at: Akiyama et al. (2019) Cryoprotectant-free Cryopreservation of Mammalian Cells by Superflash Freezing.


Source: Shinshu University; Photo: US National Academy of Sciences.
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