Encapsulation of Human Erythrocytes by Growing Ice Crystals

Lipp, G.; Galow, S.; Körber, Ch.; Rau, G.

doi:10.1006/cryo.1994.1036

Cited by 5 publications

(7 citation statements)

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“…Moreover, the model has shown that the velocity can increase by a factor of two or more when the cells are lined up in a row ahead of the solidification front. The velocities found here can be compared with the critical velocity for human erythrocytes reported by Lipp et al (1994), which is slightly above 1 m/s. Although the migration velocities appear to be too small to explain the motion of cells away from a solidification front, the phenomena can possibly be put to a practical use in measurements of cell properties.…”

Section: Discussionsupporting

confidence: 60%

“…For cells in physiological saline, they found that the cells were pushed ahead of the solidification front, often resulting in trapping of cells between advancing ice fingers during unstable cellular solidification. The pushing of cells ahead of a solidification front has been seen by other investigators (Bronstein et al, 1981;Ko ¨rber, 1988;Lipp et al, 1994), and a similar phenomena is well known in metallurgy where solidification fronts can push small particles and bubbles into the nonsolidified region. The explanation, in the case of particles, is believed to be repulsive van der Waals forces.…”

Section: Introductionsupporting

confidence: 71%

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The Osmotic Migration of Cells in a Solute Gradient

Jaeger

Carin

Médale

et al. 1999

Biophysical Journal

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The effect of a nonuniform solute concentration on the osmotic transport of water through the boundaries of a simple model cell is investigated. A system of two ordinary differential equations is derived for the motion of a single cell in the limit of a fast solute diffusion, and an analytic solution is obtained for one special case. A two-dimensional finite element model has been developed to simulate the more general case (finite diffusion rates, solute gradient induced by a solidification front). It is shown that the cell moves to regions of lower solute concentration due to the uneven flux of water through the cell boundaries. This mechanism has apparently not been discussed previously. The magnitude of this effect is small for red blood cells, the case in which all of the relevant parameters are known. We show, however, that it increases with cell size and membrane permeability, so this effect could be important for larger cells. The finite element model presented should also have other applications in the study of the response of cells to an osmotic stress and for the interaction of cells and solidification fronts. Such investigations are of major relevance for the optimization of cryopreservation processes.

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Section: Discussionsupporting

confidence: 60%

Section: Introductionsupporting

confidence: 71%

The Osmotic Migration of Cells in a Solute Gradient

Jaeger

Carin

Médale

et al. 1999

Biophysical Journal

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“…However, it is important to note that this phenomenon is strongly affected by the cell volume change that occurs continuously during interaction. This could be responsible for the significant variations in reported values [29]. In this section, we use our simulations to examine the role of various parameters that can alter the dehydration characteristics of the cell, and show that indeed they have a significant effect on the interactions that occur between the cell and the interface.…”

Section: Flat Interfacementioning

confidence: 95%

“…Several researchers have attempted to find the critical velocity that marks the boundary between pushing and engulfment of a cell by an ice interface [4,28,29,48]. However, it is important to note that this phenomenon is strongly affected by the cell volume change that occurs continuously during interaction.…”

Section: Flat Interfacementioning

confidence: 99%

Modeling the interaction of biological cells with a solidifying interface

Chang

Dantzig

Darr

et al. 2007

Journal of Computational Physics

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“…Indeed, it has long been known that during freezing, air is released and often trapped as bubbles in the resultant ice. This phenomenon has important biological consequences in that bubble formation contributes to freezing damage in long-term preservation of cells and tissues (Carte et al 1961;Karlsson et al 1993;King et al 1974;Korber 1988;Kruuv 1985;Lipp et al 1987;Lipp et al 1994;Morris et al 1981;Steponkus et al 1981;Tao et al 2002;Toner et al 1990).…”

Section: Discussionmentioning

confidence: 99%

A Method to Co-Encapsulate Gas and Drugs in Liposomes for Ultrasound-Controlled Drug Delivery

Huang

McPherson

MacDonald

2008

Ultrasound in Medicine & Biology

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A novel method for the facile production of gas-containing liposomes with simultaneous drug encapsulation is described. Liposomes of phospholipid and cholesterol were prepared by conventional procedures of hydrating the lipid film, sonicating, freezing and thawing. A single, but critical modification of this procedure generates liposomes that contain gas (air, perfluorocarbon, argon); after sonication, the lipid is placed under pressure with the gas of interest. After equilibration, the sample is frozen. The pressure is then reduced to atmospheric and the suspension thawed. This procedure leads to entrapment of air in amounts up to 10% by volume by lipid dispersions at moderate (10mg/ml) concentrations of lipids. The amount of gas encapsulated increases with gas pressure and lipid concentration. Utilizing 0.32 M mannitol to provide an aqueous phase with physiological osmolarity, 1, 3, 6 or 9 atm of pressure was applied to 4 mg of lipid. This led to encapsulation of 10, 15, 20, and 30 l of gas in a total of 400 l of liposome dispersion (10mg lipids/ml), respectively. The mechanism for gas encapsulation presumably depends upon the fact that air (predominantly nitrogen and oxygen), like most solutes, dissolves poorly in ice and is excluded from the ice that forms during freezing. The excluded air then comes out of solution as air pockets that are stabilized in some form by a lipid coating. The presence of air in these preparations sensitizes them to ultrasound (1MHz, 8 W/cm 2 ,10 second) such that up to half of their aqueous contents (which could be a water soluble drug) can be released by short (10 s) applications of ultrasound. Both diagnostic and therapeutic applications of the method are conceivable.

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Encapsulation of Human Erythrocytes by Growing Ice Crystals

Cited by 5 publications

References 0 publications

The Osmotic Migration of Cells in a Solute Gradient

The Osmotic Migration of Cells in a Solute Gradient

Modeling the interaction of biological cells with a solidifying interface

A Method to Co-Encapsulate Gas and Drugs in Liposomes for Ultrasound-Controlled Drug Delivery

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