What is a cryopreservative?
A cryopreservative is an agent or device used to freeze and preserve biological samples at extremely low temperatures, often close to -196°C through the use of liquid nitrogen . It prevents the formation of ice crystals inside cells, thus preserving their integrity and functionality after thawing.
Main applications of cryopreservative
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Biobank: Conservation of cells, DNA, sperm, oocytes or embryos.
- Biomedical research: Preservation of cell lines and biological samples.
- Pharmaceutical industry: Storage of bacterial or viral cultures for vaccine production.
- Food industry: Conservation of yeast and enzyme cultures.
How does a cryopreservative work?
The cryopreservation process relies on rapidly reducing the temperature to achieve a solid phase without massive crystal formation. The sample is first prepared in suitable laboratory equipment and then combined with cryoprotective agents such as DMSO (dimethyl sulfoxide) or glycerol. It is then gradually cooled to the desired storage temperature, often via immersion in liquid nitrogen.
The key stages of cryopreservation
- Preparation: Addition of cryoprotectants to minimize cellular damage.
- Controlled freezing: Slow cooling to avoid intracellular crystallization.
- Storage: Store at very low temperature in a liquid nitrogen cryopreservator or cryogenic freezer.
- Rapid Thawing: Rapid warming to preserve sample viability.
Why use a cryopreservative in the laboratory?
Using a cryopreservative guarantees several crucial advantages for research and medicine:
- Maintenance of cell viability: Preserved cells remain functional after thawing.
- Genetic preservation: Essential for species conservation programs and medical research.
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Secure long-term storage: Biological samples can be used years later without loss of quality.
- Cold chain optimization: Protection against microbial proliferation and oxidation.
The different types of cryopreservatives
1. Chemical cryopreservatives
These are agents such as DMSO, glycerol, or specialized commercial solutions. They penetrate cells and protect against crystallization.
2. Physical cryopreservatives
Devices such as liquid nitrogen tanks, ultra-low temperature freezers, or rapid freezing chambers provide a suitable physical environment for sample preservation.
Criteria for choosing a cryopreservative for your laboratory
When choosing a cryopreservative, several factors should be considered:
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Nature of samples: Animal cells, plant cells, embryos, gametes? Each type requires specific protocols.
- Storage volume: Depending on the quantity of samples to be stored.
- Desired shelf life: Short term or long term storage.
- Reliability and safety: Presence of alert systems in the event of a rise in temperature.
- Regulatory Compliance: Ensure that equipment meets current standards for cryopreservation.
What is liquid nitrogen used for in a cryopreservator?
Liquid nitrogen is the cornerstone of cryogenic preservation. Thanks to its extremely low boiling point (-196°C), it allows samples to be cooled rapidly and maintained at a stable temperature, preventing any bacterial proliferation or biological degradation.
Its low-pressure liquid state ensures uniform and rapid cooling, essential for preserving delicate cellular structures without the formation of harmful ice crystals.
Precautions to take with liquid nitrogen:
- Use protective gloves and goggles.
- Work in ventilated spaces to avoid asphyxiation from oxygen displacement.
- Use containers specifically designed to withstand very low temperatures.
The main applications of cryopreservatives in the laboratory
Cryopreservative plays a central role in many scientific disciplines:
- Biomedical research: Preservation of stem cells, cell lines, viruses and bacteria for repeated experiments over time.
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Fertility and medically assisted procreation: Conservation of sperm, oocytes and embryos for fertility treatments or fertility preservation before heavy medical treatments.
- Food industry: Storage of microbial strains used in the production of yogurts, cheeses, or fermented products.
- Biodiversity conservation: Genetic preservation of endangered species through the conservation of biological samples in biobanks.
Advantages and limitations of using a cryopreservative
Benefits
- Long-term stability: Possibility of storing samples for several years without significant deterioration.
- Maintenance of cell viability: Thawed samples regain their initial functionality in most cases.
- Flexibility: Wide range of cell types and samples that can be preserved.
Boundaries
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Energy costs: Requires a constant supply of liquid nitrogen or electricity to maintain low temperatures.
- Handling risks: Liquid nitrogen, if misused, presents health risks (burns, asphyxiation).
- Possible degradation: Poorly controlled thermal shock can damage cells or tissues.
What future for cryopreservation?
Research is advancing toward even more effective cryopreservation methods, including better control of crystal formation and the development of safer, less toxic cryoprotective agents. New technologies, such as ultra-rapid vitrification, are already enabling better preservation of delicate cells such as oocytes and embryos. The use of innovative materials for storage tanks and reservoirs is also improving the safety and energy efficiency of laboratory equipment.
The demand for cryopreservation is growing, particularly with the rise of cell therapy, regenerative medicine, and genetic biobanks. Investing in reliable equipment is therefore more crucial than ever.
