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Transport phenomena during freezing of adipose tissue derived adult stem cells
Author(s) -
Thirumala Sreedhar,
Gimble Jeffrey M.,
Devireddy Ram V.
Publication year - 2005
Publication title -
biotechnology and bioengineering
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.136
H-Index - 189
eISSN - 1097-0290
pISSN - 0006-3592
DOI - 10.1002/bit.20615
Subject(s) - adipose tissue , stem cell , microbiology and biotechnology , biology , chemistry , biophysics , biochemistry
In the present study a well‐established differential scanning calorimeter (DSC) technique is used to measure the water transport phenomena during freezing of stromal vascular fraction (SVF) and adipose tissue derived adult stem (ADAS) cells at different passages (Passages 0 and 2). Volumetric shrinkage during freezing of adipose derived cells was obtained at a cooling rate of 20°C/min in the presence of extracellular ice and two different, commonly used, cryoprotective agents, CPAs (10% DMSO and 10% Glycerol). The adipose derived cells were modeled as spheres of 50 µm diameter with an osmotically inactive volume ( V b ) of 0.6 V o , where V o is the isotonic cell volume. By fitting a model of water transport to the experimentally obtained volumetric shrinkage data, the “best‐fit” membrane permeability parameters (reference membrane permeability to water, L pg or L pg [cpa] and the activation energy, E Lp or E Lp [cpa]) were determined. The “best‐fit” membrane permeability parameters for adipose derived cells in the absence and presence of CPAs ranged from: L pg = 23.1–111.5 × 10 −15 m 3 /Ns (0.135–0.652 µm/min‐atm) and E Lp = 43.1–168.8 kJ/mol (9.7–40.4 kcal/mol). Numerical simulations of water transport were then performed under a variety of cooling rates (5–100°C/min) using the experimentally determined membrane permeability parameters. And finally, the simulation results were analyzed to predict the optimal rates of freezing adipose derived cells in the presence and absence of CPAs. © 2005 Wiley Periodicals, Inc.