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Mechanisms of freezing damage
1MRC Medical Cryobiology Group, University Department of Surgery, Cambridge.
Symposia of the Society for Experimental Biology
|January 1, 1987
Summary
Cell injury during freezing is primarily caused by solute concentration, not just ice formation. Cryoprotectants like glycerol may also contribute to damage, requiring careful experimental design for accurate results.
Area of Science:
- Cryobiology
- Cellular Physiology
- Biophysics
Background:
- Freezing aqueous systems causes ice formation and solute concentration.
- Cell injury at low cooling rates is often attributed to electrolyte buildup.
- Cryoprotectants are believed to mitigate this solute concentration effect.
Purpose of the Study:
- To investigate the direct effects of ice formation and solute concentration on cell injury during freezing.
- To re-evaluate existing theories on the dominant damaging factors in cryobiology.
- To assess the role of glycerol as a cryoprotectant and potential damaging agent.
Main Methods:
- Experimental freezing of human red blood cells in sodium chloride/glycerol/water solutions.
- Quantitative analysis of cell damage correlated with solute concentration.
- Re-evaluation of published data on cell responses to freezing and thawing.
Main Results:
- Cell damage in red blood cells freezing was quantitatively linked to increased solute concentration.
- Higher glycerol concentrations led to damage at lower solute concentrations, suggesting glycerol's own damaging potential.
- Alternative explanations for cell damage, including shrinkage and re-expansion, were proposed for existing data.
Conclusions:
- External ice formation may not directly damage dilute cell suspensions.
- Intracellular ice formation is directly damaging.
- Extracellular ice can damage densely packed cells (recrystallization) and tissues/organs, but results remain tentative due to experimental challenges.