A numerical study of cell behaviour in a ternary solution during the freezing process

Area of Science:

• Thermodynamics
• Biophysics
• Cryobiology

Background:

• Understanding phase change phenomena in multi-component systems is crucial for cryopreservation.
• Cellular response to freezing, including water loss and volume changes, is critical for viability.
• Ternary solutions (H2O-NaCl-CPA) are commonly used cryoprotective agents.

Purpose of the Study:

• To numerically investigate the freezing process of cell suspension in a ternary solution within a flat bag.
• To analyze temperature and phase change dynamics, intracellular water loss, and cell volume changes.
• To determine the location-dependent effects of cooling rates on cellular behavior during freezing.

Main Methods:

• A continuum model was employed to simulate the multi-component phase change system.
• Numerical calculations were performed to determine temperature, phase change history, and cellular responses.
• Analysis focused on variations across different locations within the cell suspension.

Main Results:

• Despite constant boundary cooling, internal sample locations experienced varied temperature changes and cooling rates.
• The highest cooling rates were observed at internal locations within the cell suspension.
• Cell volume changes were found to be dependent on the location within the sample.

Conclusions:

• The spatial distribution of cooling rates significantly influences cellular responses during freezing.
• Location-dependent temperature gradients and cooling rates lead to non-uniform cell volume changes.
• These findings highlight the importance of considering spatial variations in cryopreservation protocols.