Modelling the Cryopreservation Process of a Suspension of Cells: The Effect of a Size-Distributed Cell Population - Computational Modeling in Tissue Engineering - page 173

for the cooling, storage and thawing stages. To reach this goal, the model
capability to quantitatively describe system behaviour needs to be improved by
overcoming several limitations. Specifically, some physico-chemical phenomena
previously omitted that take place during the cooling phase down to cryogenic
temperatures (-196C) followed by the thawing up to 37C, will be taken into
account: a double mechanism (heterogeneous and homogeneous) of nucleation for
intra-cellular ice, vitrification-devitrification of intra- and extra-cellular water,
solution injury). This way, the whole cryopreservation cycle will be simulated
instead of limiting the description of system behaviour to only those physico-
chemical phenomena involved in the cooling phase down to a given temperature
(-40 or -60C). Since a very complex mathematical model would result if all the
physical-chemical phenomena involved during the complete cryopreservation
cycle are considered, a specific strategy will be followed to avoid ineffective
model improvements that only make harder the numerical solution. Specifically, a
sequential removal of the simplifying assumptions will be adopted, thus increasing
the complexity of the mathematical model, i.e. by continuously adding the mod-
elling improvements that will result to be effective on influencing system behav-
iour through the analysis of its numerical solution.
Acknowledgments The Fondazione Banco di Sardegna, Italy, and The Regional Government of
Sardegna are gratefully acknowledged for the finantial support of the project ''Crioconservazione
di cellule staminali da cordone ombelicale'' (2010-2011) and the fellowship within the ''Master
and Back'' program (2010-2012), respectively.
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