What happens during cryopreservation?
If cells or tissue are removed from the body, they do not remain intact for long. In principle, the same applies as with fruit or vegetables: once harvested, it lasts for a while in the refrigerator, but then begins to decompose or serves as a food source for bacteria or fungi. Food only stays “fresh” for longer if it is frozen.
This is exactly what happens to the cells during cryopreservation. The samples obtained are frozen and preserved with liquid nitrogen and thus retain their vitality until they thaw.
Cryopreservation is used for this purpose
- Oocytes: unfertilized and fertilized egg cells in the pronuclear stage, blastocysts
- Ovarian tissue
- sperm
- Testicular tissue
- Blood preserves (erythrocyte concentrate, stem cells)
- Bacteria, viruses and fungi (for scientific purposes)
- Cryopreservation of deceased persons (by American/Russian companies)
The cryopreservation of embryos is regulated by the German Embryo Protection Act (ESchG). It is only permitted in exceptional cases, namely when women wish to use the cells for their own future pregnancy.
Possible problems with cryopreservation
As sperm contain little water, there are fewer problems with cryopreservation. Egg cells, on the other hand, are difficult to freeze because they contain a lot of water. In order not to damage the cell structure with ice crystals, the water must be removed from the cell as gently as possible.
In classic cryopreservation (“slow cooling”), the cells are therefore frozen very slowly: It can take up to two hours to go from plus 20 degrees to minus 196 degrees. However, the failure rate – especially for egg cells – is high with this old method, and a large proportion of the cells are no longer viable after thawing. A newer method of cryopreservation – vitrification – is gentler.
Vitrification: a gentle process
In vitrification, the tissue is cooled down to minus 196 degrees within a very short time – namely within seconds. This gives the cells a glass-like structure (cold vitrification).
To ensure that the cell structure is not destroyed during this shock freezing, the samples are first administered a highly concentrated and expensive “antifreeze” (cryoprotection solution), which binds the water.
Cryopreservation for cancer patients
The first baby conceived with the help of a frozen and thawed egg was born in the 1980s. Since then, the method has been continuously developed. Young cancer patients in particular benefit.
This is because life-saving cancer treatment can make them infertile. Cryopreservation then offers hope. However, this is particularly expensive for women. In the past, applications for reimbursement were not always approved – and were usually time-consuming and exhausting. Cancer patients don’t have either.
Since July 1, 2021, it can be billed directly by the treating physicians. Applications to health insurance companies or even private funding for the freezing of eggs or sperm are no longer necessary.
Cryopreservation for artificial insemination
Vitrification has now also become an important part of reproductive medicine in the case of an unfulfilled desire to have children. In vitro fertilization (IVF) in particular, frozen egg cells can apparently increase the success rate for pregnancy. As several eggs can be retrieved at once and then frozen for further fertilization attempts, the physical strain on the women is less.
Cryopreservation as a lifestyle trend
Fertilization clinics, sperm banks and egg banks make it possible for women with the necessary funds to have their eggs retrieved and stored at a young age in order to fulfill their desire to have children at a later date.
Cryopreservation: costs
The costs for vitrification include freezing and the material required for this – hormonal stimulation, cycle control and transfer are not included. The costs per egg cell amount to around 350 to 500 euros, while a portion of sperm cells is slightly cheaper at around 300 to 400 euros. For both types of cells, there are subsequent six-monthly storage costs of around 100 to 200 euros. If the cells are to be thawed again, there is another bill. Around 500 to 600 euros must be paid for the thawing cycle.
You cannot expect health insurance companies (whether statutory or private) to reimburse the costs of cryopreservation. There are only exceptions in the case of impending infertility due to cancer treatment. Ask your health insurance provider about this.
Risks of cryopreservation
Ethical concerns
The legal and ethical gray areas in the storage of cryopreserved cells pose greater problems. What should happen to the large number of unused egg cells and who – in the event of the death of a donor – may dispose of the cells remains a matter for discussion. In recent years, there have been repeated court cases about the whereabouts of these so-called “snowflake babies”. The German Ethics Council has issued an opinion in favor of the donation/adoption of embryos from cryopreservation.
