Measurement of Critical Osmotic Pressure of Biological Cells : Minimum Cell-to-Volume Ratio as an Estimation of Viability

The critical osmotic pressure that can be endured by biological cells is measured. Optimal parameters of the freezing process as well as the prefreezing process are restricted by the critical osmotic pressure, which can be translated into the critical normalized volume of the cell. Viability of the cells is measured after the cells are exposed to a certain osmotic pressure, and the viability can be estimated from the viewpoint of biophysical functions. In this study, endothelial cells and smooth muscle cells comprising porcine arteries are selected as samples. The viability of endothelial cells is estimated by a dye-exclusion test, and that of smooth muscle cells is estimated by measuring the contraction-relaxation rate. Optimal parameters of the freezing process as well as the prefreezing process can be obtained by estimating the normalized volume of the cell. The critical normalized volume of cells can be estimated from the measured critical osmotic pressure.