Cell Damage due to Osmotic Stress and Microscale Mass Transfer relative to Cryopreservation

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In this study, cell damage and death due to the hypertonic electrolyte solution under the unfrozen condition were investigated experimentally in relation to the potential causes of freezing damage of cells. Next, a mathematical model with a form of reaction kinetics was proposed and developed for the cell damage and death.1) The cells from a human prostatic adenocarcinoma cell line (PC-3) were exposed from an isotonic solution (physiological saline) to hypertonic electrolyte solution (NaCl concentration C_m and exposure time τ) back to the isotonic solution under a constant temperature, T℃. Then, the cell membrane integrity was assessed in physiological saline at 25℃ to measure the cell viability. T was set at three values between 4 and 25℃, C_m at four values between 1.8 and 4.0M, and τ at seventeen values between 2 and 170min.2) From the experimental results, survival curve of cell as a function of τ, probability distribution and probability density function of cell death, characteri … More stic exposure times of cell death, etc. were obtained to clarify the dependency of them on τ, C_m, and T.3) The cell viability decreased with increasing exposure time. The decrease in viability was steeper at a higher concentration and higher temperature. When a characteristic exposure time for the decrease in cell viability was defined as exposure time τ_<0.5> at 0.5 in cell viability, the viability versus nondimensional exposure time τ/τ_<0.5> had a similar distribution independently of concentration and temperature. This means that the cell damage and death proceed kinetically and similarly, suggesting that the mechanism may be also similar.4) The cell damage and death process was formulated with a kinetic model of two-step damage on the basis of experimental results of the cell viability. Here, three states of cells : vigorous, damaged but living (medium state), and dead were considered. Four kinds of model were proposed and investigated. A reaction rate constant in the model was determined by the inverse problem analysis and the best model of four was determined. The cell viability was simulated successfully by the analytical solution from the present model. Also, the probability distribution and probability density function of cell death, and reaction kinetic properties were obtained. The reaction kinetic constant increased with an increase in C_m and T. Less