Various Approaches to Modeling the Lyopreservation of Cells

Engineering Sciences & Applied Mathematics  

Northwestern University

Certain organisms can survive in the most extreme of living conditions by entering anhydrobiosis, a waterless hibernative state. Lyopreservation seeks to duplicate this process in mammalian cells as an alternative to cryopreservation. If successful, lyopreserved cells could be stored indefinitely at room temperature, eliminating the need for the extreme temperatures or cryoprotectants required for cryopreservation. However, current techniques fail to produce viable cells after the drying process. The problem is believed to lie with the formation of trehalose glass. When combined with water, trehalose can form a glassy substance that is believed to provide protection and support to the cell membrane and organelles during the drying process. However, uncontrolled formation of this glass can actually hinder the drying process. Thus, an understanding of trehalose glass formation is key to developing successful and efficient lyopreservation techniques. To this end, the diffusion of water through a trehalose glass is modeled using subdiffusion. The equations and boundary conditions are derived using a continuous-time random walk and solved numerically. Additionally, the effect of drying on the cell membrane is modeled using incompressible Navier-Stokes. Numerically simulated cell shapes give insight into the effectiveness of various drying approaches.