Numerical modelling of cell dehydration during cryopreservation

Abstract

Cryopreservation is a novel and innovative technique for preserving cells or tissues by cooling to sub-zero temperatures. During the process the transport of water takes place across the cell membrane. The chemical potential difference arising due to different concentrations across the cell membrane is responsible for this transport. The water transportation depends on many parameters, e.g. cell level parameters such as membrane
permeability to water Lpg, activation energy ELp, and available surface area to water volume ratio SA/WV, the initial concentration of cryoprotective agent (CPA), and the
cooling rate. The membrane limited water transport model is utilized to study the effect of above mentioned parameters on the dehydration of cell and an optimal cooling rate is
obtained for which one can have maximum viability. Here, the optimal cooling rate is defined as the highest cooling rate for which amount of trapped water inside the cell is
equal to 5% of the initial cell water content at the end of preservation process where the end temperature is considered to be -400C. The criterion for selecting -400C as the end temperature and its effect on the optimal cooling rate have also been discussed in detail.
Based on the predicted optimal cooling rate, a correlation is established between theoptimal cooling rate, cell level parameters, and the initial concentration of CPA with a
goodness of fit 99.6%.