Thermodynamic modeling and cryomicroscopy of cell-size, unilamellar, and paucilamellar liposomes

Study of the Freezing Behavior of Liposomes

“…The value of k g in the present experiment was smaller by two orders of magnitude than that of egg lecithin liposomes ( (9,14) . In addition, the value of ∆E in the experiment was of an order of magnitude larger than human erythrocytes (approx.…”

“…Liposomes, closed vesicles comprising a lipid bilayer, are widely used as cell models in the investigation of cell membrane structure and function (6) . As the cell membrane is believed to be the main part of the cell that sustains damage when the cell is frozen, liposomes are also used as models in freezing experiments (7)(8)(9) . Siminovitch et al (7) discovered that both liposomes and biological cells undergo dehydration contraction with slow refrigeration and internal freezing with fast refrigeration, showing major similarities.…”

“…Morris et al (8) investigated multilamellar liposomes and observed a relationship between freezing behavior and membrane structure and the effectiveness of cryoprotectants. Callow et al (9) used unilamellar liposomes the size of large cells to compare the experimental results of volumetric changes during freezing with the results of a simulation using a thermodynamic model of osmotic pressure. Nevertheless, there have been almost no systematic studies of the mechanisms of freezing damage, nor of the effects of liposome size and the rate of cooling on freezing damage.…”

Transport phenomena during freezing of isolated hepatocytes

“…This insensitivity of 50Tl,, to the cooling rate has been shown for many other cell types in the absence of cryoprotective agents (Morris and McGrath, 1981;Callow and McGrath, 1985;Scheiwe and Korber, 1987;Shabana and McGrath, 1988;Muldrew and McGann, 1990;Toner et al, 1992;Pitt et al, 1991;Hubel et al, 1991). Although the cooling rate dependence of 5oT[IF is negligible, the theoretical and experimental observations show a noticeable depression which occurs at -108"C/min (at the transition zone when the cumulative incidence of IIF increases from 0 to 100CVo).…”

Emerging Role for Use of Liposomes in the Biopreservation of Red Blood Cells

“…Crowe et al [66][67][68] pioneered the use of liposomes as model membranes to study mechanisms by which trehalose protects cell membranes during lyophilization. Other investigators focused on liposomes as tools to characterize cell behavior during freezing, thawing and vitrification, ice propagation, phospholipid liquid crystalline-gel phase transition temperatures as well as the cryoprotective action of permeating and nonpermeating additive solutions [69][70][71][72][73][74][75][76]. Recently, liposomes have also been applied in the biopreservation field as means of improving cell recovery during freeze drying [76][77][78][79][80].…”