Host: The Japan Society of Mechanical Engineers
Name : [in Japanese]
Date : September 11, 2022 - September 14, 2022
Cryopreservation is widely used for the stable and long-term storage of cells in various fields. To inhibit ice crystal generation, at least one cryoprotective agent (CPA) must be added. We previously reported a CPA-free cryopreservation method based on inkjet technology. To achieve vitrification of cells, tiny droplets containing cells are deposited at intervals of 200 μm on the liquid nitrogen-cooled substrate, which confines the number of cells in a single operation. In this study, we aim to increase the number of droplets containing cells on the substrate by reducing the intervals between the droplets. To inhibit an influence on the cell viability, the temperature rise of formerly deposited droplets and the decrease in the cooling rate were analyzed and evaluated. The temperature of the neighboring droplet did not exceed the glass transition temperature, over which recrystallization ultrarapidly occurs, even when the droplet interval was 75 μm. On the other hand, the cooling rate at the intervals of 125 μm was slightly below the critical cooling rate of the cell. Therefore, the intervals between the droplets should be above 150 μm. We also experimentally confirmed that the cell viability at the intervals of 150 μm was the same and the viability at the intervals of 75 μm decreased by approximately 40% compared to the one at the intervals of 200 μm. Both the results suggest that CPA-free cryopreservation achieves by depositing 70pL droplets at intervals above 150 μm.
