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Seminar: Mathematical modeling of cryopreservation processes

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Zoom Meeting
Robyn Shuttleworth, University of Saskatchewan

Robyn Shuttleworth, University of Saskatchewan

Title/Abstract: Mathematical modeling of cryopreservation processes

Cryopreservation is the process of cooling and storing cells, or tissues, at very low temperatures to maintain their viability. There are four stages to successfully cooling and thawing cells or tissues, each coming with their own challenges. We will place focus on the first and final stage, namely the addition and removal of cryoprotective agents (CPAs) to the tissue. CPAs are used to reduce the likelihood of intracellular ice, and mitigate the effects of high subzero salt concentrations. During the CPA loading process, cells go through an exchange of water, via osmosis, and CPAs, via diffusion, causing a shrink/swell behaviour.

Many models have been developed to describe the loading of CPAs into either individual cells, or into a thin slab of tissue, however there have been few reports of the two models being combined. Here we propose a model that builds upon a triphasic model for articular cartilage introduced by Abazari et. al. in 2009, using a system of partial differential equations to describe the mass transport of each component, namely, water, CPA, salt, and the solid matrix. Within this system we incorporate the well-known two-parameter model to describe the cell membrane transport of both water and CPA within individual cells. Combining these two systems allows us to investigate the stress placed on the tissue by considering the interactions at both an extracellular and intracellular fluid level.

In addition, this general model allows us to specify properties of a tissue, ranging from its structure and composition, i.e. the spatially dependent percentage of tissue solids and cells or the hydraulic conductivity and CPA permeability of the embedded cells. By defining a bath solution containing a CPA concentration, our model is able to predict the CPA, salt, and water concentrations inside and outside of cells as a function of space and time in the tissues. This allows calculation of the spatial dependence of stress/strain in the tissue during CPA loading as well as the local CPA toxicity. We can adapt the percentage of cells in our tissue to investigate how cell density affects the overall stress/strain placed on a tissue during CPA loading. Ultimately, we will use our results to predict and test optimised loading protocols to reduce the overall strain and CPA toxicity during CPA loading in different tissues.

*For zoom meeting information of the seminars, please contact Dr. Qixuan Wang
Type
Seminar
Sponsor
ICQMB
Admission
Free
Registration Required
No