Working with Dr Tom Whale (Chemistry) we have demonstrated how controlling ice formation outside of cells can help reduce intracellular ice formation, during the cryopreservation of monolayers and spheroids. During cryopreservation in low volumes, water can supercool (i.e not freeze at zero), which means cells are exposed to supercooled liquid water which leads to increase intracellular ice formation, which can be fatal. The team used extracts from pollen, known to nucleate ice at warmer temperatures, to prevent supercooling and show this reduces the amount of ice inside cells. Due to the the cryopreservation of the cells, in both monolayer and spheroid format, was dramatically improved. This method is appealing as it only involves changing the the solution outside of the cells, to mitigate an intracellular process, rather than delivering a new cryoprotectant into the cells.

Chemically Induced Extracellular Ice Nucleation Reduces Intracellular Ice Formation Enabling 2D and 3D Cellular Cryopreservation