The Procedure of Cryopreservation What is Cryopreservation?
Cryopreservation is the process of preserving live cells, tissues, and other biological samples by placing them in a deep freezer at extremely low temperatures. The sample is typically stored at -196°C or lower. At such low temperatures, a cell stops undergoing all biological activity and dies. Cryopreservation makes it possible for cells to resist freezing and thawing. Ice formation within cells has the potential to rupture the cell membrane. This can be avoided by controlling the freezing rate and carefully selecting the freezing medium.
Cryopreservation Process
Biological materials such as cells, oocytes, spermatozoa, tissues, pre-implantation embryos, ovarian tissues, organs, and so on are kept in extremely cold temperatures without affecting cell viability. This approach frequently makes use of dry ice and liquid nitrogen.
The Procedure of Cryopreservation
The following are the complete cryopreservation procedure in preserving the obtained biological samples:
- Harvesting or Material Selection: When choosing biological materials, it’s vital to consider factors including volume, density, pH, morphology, and damage-free status.
- Cryoprotective agent addition – Cryoprotective agents are added to the samples to lower the freezing point of the medium and to enable a slower cooling rate, which lowers the risk of crystallisation. Examples of these agents include glycerol, FBS, salts, sugars, and glycols.
- Freezing – Different methods of freezing are used in this method of cryopreservation to protect cells from damage and cell death caused by exposure to cryoprotective agent warm solutions.
- Storage in liquid nitrogen- Cryopreserved samples are kept in a freezer at -80°C for at least 5 to 24 hours before being transferred to storage vessels.
- Thawing- The process of warming biological samples to control the rate of cooling and avoid cell damage caused by crystallisation.
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Cryopreservation Techniques
In some cases such as cancer or other problems, preserving fertility becomes critical. Couples in this situation can have biological children once their health is restored. The advancement of technology has made it possible to preserve fertility through a variety of methods. Cryopreservation is one method of freezing sperm or eggs, as well as embryos.
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Cryopreservation Methods
Fertility preservation techniques give women and men more options for family planning. Cryopreservation techniques entail freezing sperms, eggs, or embryos at extremely low temperatures (sub-zero) in compounds such as liquid nitrogen. Because low temperatures stop all biological activity in cells, they can live indefinitely. The sperms or embryos are fertilised or used in a treatment cycle when they are required.
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Freezing of Sperm
With IVF and other similar techniques, a man can preserve his sperm for future childbearing. A man must provide a sample for preservation. If there are no sperms, a surgical sperm extraction can be performed to extract sperms directly from the testicles. These are kept in a bank until they are needed for various fertility procedures.
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Freezing Eggs
After the age of 35, it becomes difficult for women to conceive. In such cases, egg freezing is an excellent option. Women can freeze their eggs in laboratories when they are young in order to have children later in life. Furthermore, females who must undergo chemotherapy can freeze their eggs prior to the treatment.
If a woman decides to freeze her eggs, she must take medications for a few days to stimulate her ovaries, allowing her to produce many more eggs than usual. When the eggs are mature enough, they are extracted from the ovarian follicles and frozen in laboratories.
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Freezing of Embryos
Embryos are preserved by collecting and storing eggs. The eggs are now fertilised with the partner’s sperm during the IVF process. The resulting embryos are cultured, allowing cell division to reach its peak. Embryos are formed and stored at a fertility clinic until they are ready to be transferred.
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Benefits of Cryopreservation
The cryopreservation technique has numerous advantages. These are some examples:
- Treatments for infertility.
- There is very little space and labour required.
- Protection against genetic contamination.
- Protects the genetic integrity of valuable stains.
- Protects endangered species’ germplasm.
- Biological samples can be stored for an extended period of time.
- The samples are protected from disease and microbial contamination.
- Cryopreservation of gametes, embryos, and other cells prevents genetic drift.
Applications of Cryopreservation
Cryopreservation is a long-term storage technique that is primarily used to preserve and maintain the viability of biological samples for a longer period of time.
This preservation method is widely used in a variety of fields, including cryosurgery, molecular biology, ecology, food science, plant physiology, and many medical applications. Other uses for the cryopreservation process include:
- In vitro fertilization
- Gene Bank
- Blood transfusion
- Seed Bank
- Organ transplantation
- Artificial insemination
- Storage of rare germplasm
- Freezing of cell cultures
- Conservation of endangered plant species
- Biodiversity conservation
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