Cryomicroscopic analysis of intracellular ice formation in porcine iliac endothelial cells upon cooling.

　　BACKGROUND: Intracellular ice formation (IIF) plays an important role in cryopreservation and cryosurgery. IIF in porcine iliac endothelial cells (PIECs) has not been fully investigated.

OBJECTIVE: To analyze the phenomenon of IIF in PIECs during freezing.

MATERIALS AND METHODS: The cryomicroscopy system was used for observation of the cell morphology and for the count of IIF during freezing, while the theoretical model for probability IIF (PIF) was used to determine the nucleation kinetic and thermodynamic parameters.

RESULTS: PIF was observed at 40, 80 and 100 degree C/min upon cooling and 100 degree C/min upon warming, in the presence and absence of 1 M dimethyl sulfoxide (Me2SO). The kinetic and thermodynamic parameters were obtained by fitting the PIF model to experimental data.

CONCLUSION: PIF increases along with the increased cooling rate. The addition of 1 M dimethyl sulfoxide (Me2SO) decreases the onset IIF temperature, but increases PIF. Cooling rate and Me2SO concentration significantly affect IIF. The finding has significant implications in both cryopreservation and cryosurgery.