Cryopreservation

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Nicole Wendler holds a PhD in biology in the field of oncology and immunology. As a medical editor, author and proofreader, she works for various publishers, for whom she presents complex and extensive medical issues in a simple, concise and logical manner.

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With cryopreservation, plant, animal or human cells can be frozen and stored without losing their vitality. This also applies to sperm and egg cells! Cancer patents in particular benefit. But also people who want to have children later. Read everything you need to know about cryopreservation and the advantages and disadvantages associated with it!

What happens with cryopreservation?

If cells or tissues are removed from the body, they do not remain intact for long. In principle, the same applies as for fruit or vegetables: once they have been harvested, they stay in the refrigerator for a while, but then begin to decompose or serve as a food source for bacteria or fungi. Food stays "fresh" longer only 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 are thawed.

Cryopreservation is used for this

• Egg cells: unfertilized and fertilized egg cell in the pronuclear stage, blastocyst
• Ovarian tissue
• sperm
• Testicular tissue
• Blood reserves (packed red blood cells, stem cells)
• Bacteria, viruses and fungi (for scientific purposes)
• Cryopreservation of the deceased (by American / Russian companies)

The cryopreservation of embryos is regulated by the German Embryo Protection Act (ESchG). It is only allowed in exceptional cases, namely when women want to use the cells for their own later pregnancy.

Possible problems with cryopreservation

The process of freezing is not without its problems. Crystals quickly form below zero from the water in the cells and destroy important cell components. It is essential to prevent this with cryopreservation.

Because sperm contain little water, they have 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 In order not to damage the cell structure with ice crystals, the water must be withdrawn from the cell as gently as possible.

With classic cryopreservation ("slow cooling"), the cells are frozen very slowly: it can take up to two hours to get from plus 20 degrees to minus 196 degrees. But the failure rate - especially with egg cells - is high with this old method, and a large number of the cells are no longer viable after thawing. A newer method of cryopreservation - vitrification - is gentler on the other hand.

Vitrification: gentle cryopreservation

During 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 glazing).

To ensure that the cell structure does not break during this shock freezing process, the samples are given a highly concentrated and expensive "antifreeze" (cryoprotection solution) which binds the water.

The thawing process is also quick during vitrification. Here the antifreeze protects against the rapid influx of water into the cell (rehydration). In this way, up to 90 percent of the frozen cells ultimately survive during vitrification.

Cryopreservation for cancer patients

The first baby to be conceived using a frozen and thawed egg cell saw the light of day in the 1980s. Since then, the method has been continuously developed. Young cancer patients in particular benefit.

Because the life-saving cancer treatment can make you sterile. Cryopreservation then offers hope. But this is expensive, especially for women. Applications for reimbursement were by no means always approved in the past - and were mostly time-consuming and exhausting. Cancer patients do not have both.

From July 1, 2021, it can be billed directly by the treating physicians. There are no applications to the health insurance companies or even private funding for the freezing of egg cells or sperm.

Cryopreservation for artificial insemination

In the meantime, vitrification has also become an important part of reproductive medicine when the desire to have children is unfulfilled.Frozen egg cells appear to increase the success rate for pregnancy, especially with in vitro fertilization (IVF). Since several egg cells can be removed at once and then frozen for further fertilization attempts, the physical stress for the women is less.

Cryopreservation as a lifestyle trend

In Germany it is allowed to freeze your own fertilized or unfertilized egg cells or sperm for an indefinite period of time. What was intended as an offer for women and men with a medical indication is now increasingly shifting to the lifestyle area under the term "social freezing".

Fertilization clinics, sperm banks, but also egg banks enable women with the necessary change to have their eggs removed and stored at a young age in order to later fulfill their desire to have children at a desired time.

Cryopreservation: cost

The cost of vitrification includes freezing and the material required for it - hormonal stimulation, cycle control and transfer are not included. The costs per egg are around 350 to 500 euros, while a portion of sperm cells is a little cheaper at around 300 to 400 euros. For both cell types, there are then half-yearly costs for storage of around 100 to 200 euros. If the cells are to be thawed again, there is another calculation. Around 500 to 600 euros have to be paid for the thawing cycle.

A reimbursement of the costs for the cryopreservation cannot be expected from the health insurances (regardless of whether it is statutory or private). Exceptions are occasionally only in the case of impending infertility due to cancer therapy. Inquire about this with your health insurance company.

Risks of cryopreservation

Long-term data on possible birth defects, complications and high-risk pregnancies have not yet been conclusively assessed in connection with cryopreservation. With around 1,000 healthy children conceived by artificial insemination each year, the risks seem low.

Ethical concerns

The legal and ethical gray areas in the storage of cryopreserved cells cause greater problems. It remains to be discussed 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. In recent years there have been repeated court hearings about the whereabouts of these so-called "snowflake babies". The German Ethics Council issued a statement in favor of the donation / adoption of embryos from cryopreservation.

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