TY - JOUR

T1 - Cryo-responses of two types of large unilamellar vesicles in the presence of non-permeable or permeable cryoprotecting agents

AU - Siow, Lee Fong

AU - Rades, Thomas

AU - Lim, Miang Hoong

PY - 2008

Y1 - 2008

N2 - Cryo-responses of two types of large unilamellar vesicles (LUV) that were made from either egg yolk L-alpha-phosphatidylcholine (EPC) or 1,2-dipalmitoyl-rac-glycero-3-phosphocholine (DPPC), in the presence of non-permeable or permeable cryoprotective agents (CPA) was investigated. Partial ternary phase diagrams of CPA-salt-water with specific CPA to salt ratio (R), were constructed to estimate the phase volume of ice and unfrozen matrix of the LUV dispersion, which could aid in understanding the mechanistic actions of CPA. Leakage of both EPC and DPPC LUV was reduced if the sugar concentrations are above 10% (w/w) for disaccharides and 5% (w/w) for monosaccharides. Above these sugar concentrations, non-permeable CPA were more effective in preventing leakage of DPPC LUV than in EPC LUV. Below these sugar concentrations, EPC and DPPC LUV with limited mobility in the remaining unfrozen matrix were more likely to approach and interact with one and another, which were not anticipated when the LUV were completely embedded in the ice matrix. In the presence of Me(2)SO or EG, EPC LUV that had been subjected to freezing and thawing processes were protected from leakage. At room temperature, Me(2)SO and EG were detrimental to the DPPC LUV. This study suggests that the choice of CPA for cell cryopreservation depends on the type of phospholipids in plasma membranes, which vary in their acyl chain length and gel-liquid crystal phase transition temperature.

AB - Cryo-responses of two types of large unilamellar vesicles (LUV) that were made from either egg yolk L-alpha-phosphatidylcholine (EPC) or 1,2-dipalmitoyl-rac-glycero-3-phosphocholine (DPPC), in the presence of non-permeable or permeable cryoprotective agents (CPA) was investigated. Partial ternary phase diagrams of CPA-salt-water with specific CPA to salt ratio (R), were constructed to estimate the phase volume of ice and unfrozen matrix of the LUV dispersion, which could aid in understanding the mechanistic actions of CPA. Leakage of both EPC and DPPC LUV was reduced if the sugar concentrations are above 10% (w/w) for disaccharides and 5% (w/w) for monosaccharides. Above these sugar concentrations, non-permeable CPA were more effective in preventing leakage of DPPC LUV than in EPC LUV. Below these sugar concentrations, EPC and DPPC LUV with limited mobility in the remaining unfrozen matrix were more likely to approach and interact with one and another, which were not anticipated when the LUV were completely embedded in the ice matrix. In the presence of Me(2)SO or EG, EPC LUV that had been subjected to freezing and thawing processes were protected from leakage. At room temperature, Me(2)SO and EG were detrimental to the DPPC LUV. This study suggests that the choice of CPA for cell cryopreservation depends on the type of phospholipids in plasma membranes, which vary in their acyl chain length and gel-liquid crystal phase transition temperature.

U2 - 10.1016/j.cryobiol.2008.09.011

DO - 10.1016/j.cryobiol.2008.09.011

M3 - Journal article

C2 - 18854181

VL - 57

SP - 276

EP - 285

JO - Cryobiology

JF - Cryobiology

SN - 0011-2240

IS - 3

ER -