Quick answer
Cryopreservation media should protect cells during freezing while limiting post-thaw stress
Cryopreservation media protect cells from damage during freezing and long-term low-temperature storage. Without appropriate protection, extracellular and intracellular ice formation, solute concentration changes, and osmotic stress can disrupt membranes and reduce viability.
Cryoprotective agents help control these effects. DMSO is widely used for mammalian cell preservation, while glycerol is valuable for selected biological materials and cell types. Emerging formulations increasingly combine multiple protective strategies to improve recovery and reduce toxicity.
What Is Cryopreservation Media?
A cryopreservation medium typically combines a basal medium or buffered solution with one or more cryoprotective agents (CPAs).
CPAs reduce freezing injury by influencing ice formation, water movement, and solute concentration during cooling.
Cryoprotectants are often classified as penetrating or non-penetrating. Penetrating agents can cross cell membranes and protect intracellular structures, while non-penetrating compounds primarily influence the extracellular environment and membrane stabilization.
The appropriate formulation depends heavily on cell type.
DMSO as a Cryoprotectant
Dimethyl sulfoxide (DMSO) is one of the most widely used penetrating cryoprotectants for mammalian cells.
DMSO enters cells and reduces damaging ice formation during cooling. Many conventional mammalian cell freezing formulations contain approximately 5–10% DMSO, although the optimal concentration varies.
The principal drawback is toxicity.
DMSO becomes increasingly harmful to many cells as temperature rises. Cells should therefore spend as little unnecessary time as possible in DMSO-containing freezing medium at room temperature.
During thawing, rapid processing and prompt removal or substantial dilution of DMSO can improve recovery.
Glycerol as an Alternative
Glycerol is another penetrating cryoprotectant that reduces freezing injury.
It has a long history of use for microorganisms and selected blood-derived cells, particularly red blood cells, as well as some other biological preparations.
Glycerol typically permeates mammalian cell membranes more slowly than DMSO. This can influence equilibration and post-thaw removal requirements.
For many conventional cultured mammalian cell lines, DMSO remains more commonly used, while glycerol is favored in particular specialized preservation workflows.
DMSO vs Glycerol: Key Differences
Neither compound is universally superior. Cryoprotectant concentration, cooling rate, equilibration, storage temperature, and thawing procedure all influence outcome.
Emerging Alternatives to DMSO and Glycerol
Ethylene Glycol
Ethylene glycol is a penetrating cryoprotectant used in selected cell, tissue, embryo, and vitrification workflows. Its suitability depends on the biological system.
Trehalose
Trehalose is a non-reducing sugar that can help stabilize membranes and proteins during freezing and dehydration.
Because trehalose does not readily cross intact mammalian cell membranes, its effectiveness can depend on formulation and delivery strategy.
Serum-Free Cryopreservation Formulations
Serum-free freezing media reduce reliance on animal-derived serum and can improve formulation consistency.
Some formulations combine reduced DMSO concentrations with sugars, polymers, proteins, or other protective compounds.
How to Choose a Cryopreservation Medium
Begin with a validated procedure for the specific cell type.
Evaluate not only immediate post-thaw viability but also attachment, proliferation, phenotype, differentiation capacity, and functional performance after recovery.
A formulation that produces high initial viability but alters downstream cell behavior may not be appropriate.
Cell-type-specific validation is essential. Primary cells, stem cells, immune cells, and established cell lines can respond very differently to the same freezing formulation.
FAQ
Common questions
Why is DMSO used so frequently?
It penetrates cells effectively and provides strong protection against freezing injury for many mammalian cell types.
Is DMSO toxic?
Yes. Toxicity increases with concentration, exposure time, temperature, and cell sensitivity.
Can glycerol replace DMSO directly?
Not necessarily. Glycerol has different permeability and biological effects and should be validated for the specific cell type.
Are DMSO-free freezing media available?
DMSO-free and reduced-DMSO approaches exist, but performance varies by cell type and should be experimentally validated.
Products
Products used in this workflow
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