title: The effect of EIF dynamics on the cryopreservation process of a size distributed cell population.
abstract: Typical mathematical modeling of cryopreservation of cell suspensions assumes a thermodynamic equilibrium between the ice and liquid water in the extracellular solution. This work investigates the validity of this assumption by introducing a population balance approach for dynamic extracellular ice formation (EIF) in the absence of any cryo-protectant agent (CPA). The population balance model reflects nucleation and diffusion-limited growth in the suspending solution whose driving forces are evaluated in the relevant phase diagram. This population balance description of the extracellular compartment has been coupled to a model recently proposed in the literature [Fadda et al., AIChE Journal, 56, 2173-2185, (2010)], which is capable of quantitatively describing and predicting internal ice formation (IIF) inside the cells. The cells are characterized by a size distribution (i.e. through another population balance), thus overcoming the classic view of a population of identically sized cells. From the comparison of the system behavior in terms of the dynamics of the cell size distribution it can be concluded that the assumption of a thermodynamic equilibrium in the extracellular compartment is not always justified. Depending on the cooling rate, the dynamics of EIF needs to be considered.
authors.affiliation: Dipartimento di Ingegneria Chimica e Materiali, Università degli Studi di Cagliari, Piazza d'Armi, 09123 Cagliari, Italy.
authors.forename: S
authors.initials: S
authors.lastname: Fadda
authors.forename: H
authors.initials: H
authors.lastname: Briesen
authors.forename: A
authors.initials: A
authors.lastname: Cincotti
mesh_terms: D016477:Artifacts; D002462:Cell Membrane; D002463:Cell Membrane Permeability; D048429:Cell Size; D003080:Cold Temperature; D003198:Computer Simulation; D015925:Cryopreservation / Q000379:methods*; D003451:Cryoprotective Agents / Q000737:chemistry; D004058:Diffusion; D005615:Freezing; D007053:Ice / Q000032:analysis*; D007700:Kinetics; D008954:Models, Biological; D012965:Sodium Chloride / Q000737:chemistry; D012996:Solutions / Q000737:chemistry; D013816:Thermodynamics; D014867:Water
chemical_list: D003451:Cryoprotective Agents; D007053:Ice; D012996:Solutions; D014867:Water; D012965:Sodium Chloride