A numerical study on distributions during cryoprotectant loading caused by laminar flow in a microchannel

Abstract

In this work, we conduct a computational study on the loading of cryoprotective agents into cells in preparation for cryopreservation. The advantages of microfluidics in cryopreserving cells include control of fluid flow parameters for reliable cryoprotectant loading and reproducible streamlined processing of samples. A 0.25 m long, three inlet T-junction microchannel serves as an idealized environment for this process. The flow field and concentration distribution are determined from a computational fluid dynamics study and cells are tracked as inert particles in a Lagrangian frame. These particles are not confined to streamlines but can migrate laterally due to the Segre-Sildeberg effect for particles in a shear flow. During this tracking, the local concentration field surrounding the cell is monitored. This data are used as input into the Kedem-Katchalsky equations to numerically study passive solute transport across the cell membrane. As a result of the laminar flow, each cell has a unique pathline in the flow field resulting in different residence times and a unique external concentration field along its path. However, in most previous studies, the effect of a spatially varying concentration field on the transport across the cell membrane is ignored. The dynamics of this process are investigated for a population of cells released from the inlet. Using dimensional analysis, we find a governing parameter a, which is the ratio of the time scale for membrane transport to the average residence time in the channel. For a <¼ 0:224, cryoprotectant loading is completed to within 5% of the target concentration for all of the cells. However, for a > 0:224, we find the population of cells does not achieve complete loading and there is a distribution of intracellular cryoprotective agent concentration amongst the population. Further increasing a beyond a value of 2 leads to negligible cryoprotectant loading. These simulations on populations of cells may lead to improved microfluidic cryopreservation protocols where more consistent cryoprotective agent loading and freezing can be achieved, thus increasing cell survival. V C 2013 American Institute of Physics. [http://dx

Continuous removal of glycerol from frozen-thawed red blood cells in a microfluidic membrane device

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Microfluidics for cryopreservation

“…Chandran and colleagues (Bala Chandran et al, 2012) investigated the influence of buoyancy-driven flow on mass transfer in a two-stream microfluidic channel, and successfully introduced the typical CPA (10% v/v DMSO) into a cell suspension (Jurkat cells) using this device (Figure 7A). Scherr and co-workers (Scherr et al, 2013) conducted a numerical study of flow field and the concentration distribution during CPA loading into cells in a three inlet T-junction microchannel, and found that each cell has a unique path in the flow field, and thus a distinctive extracellular concentration profile (Figure 7B). For practical use with more realistic and more complicated mixtures of cryoprotectants, they then simulated loading of cryoprotectant cocktails-on-a-chip (Scherr et al, 2014a, b).…”

“…(E) A sequential logarithmic microfluidic mixer for zebrafish sperm activation. Reproduced from (Bala Chandran et al, 2012; Lusianti and Higgins, 2014; Scherr et al, 2013; Song et al, 2009)(Scherr et al, 2015) with permission.…”

Microfluidics and numerical simulation as methods for standardization of zebrafish sperm cell activation

“…The small scale, on the order of microns, allows unique analysis and processing conditions over a wide range of cellular phenomena, including: cell motility and migration (Ricart et al 2011), cryopreservation (Song et al 2009; Scherr et al 2013; Fleming et al 2007), as well as cell detection and filtration (Henslee et al 2011). A potential remedy to the problems with sperm activation studies, microfluidic devices offer these activation studies both high throughput and high reproducibility.…”

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