For many couples struggling to conceive, fertility treatment is the only way to start a family. Cryopreservation plays an important role in modern reproductive medicine.
Eggs or sperm are preserved by freezing them in liquid nitrogen. They are then available for artificial insemination. This can be a useful option if there is a risk of imminent infertility (due to cancer treatment or menopause).
Here you will find information about the medical applications and procedures involved in cryopreservation, as well as specialists in the field.
Body cells (somatic cells) can be preserved for several years by freezing and storing them in liquid nitrogen.
The low temperatures ensure that biological processes such as cell death and DNA degradation are halted, and the cells’ condition remains unchanged. The frozen eggs or sperm are therefore just as viable after thawing as they were before.
Cryopreservation allows cells and tissues to be stored for long periods of time for later use @ sola_sola /AdobeStock
The problem with cryopreservation is the formation of ice crystals during the process. These crystals cause cell damage and cell death. For this reason, experts use cryoprotective solutions to minimize the risk of ice crystal formation.
This method is also known as vitrification and is an alternative to “slow freezing.” In this process, the cells are treated with high concentrations of cryoprotectants. These draw fluid out of the cells and transform them into a glass-like state. This is how experts prevent the formation of ice crystals.
Infertility—Preventive Care with Cryopreservation
A pregnancy requires both viable male sperm and a viable female egg. If either of these germ cells is non-viable, fertilization fails, preventing the formation of an embryo.
If infertility is a threat or is foreseeable, cryopreservation is a viable option for preserving viable eggs or sperm. Viable eggs or sperm are needed for various reasons.
Reasons for Women
Infertility naturally begins during menopause. Perimenopause—the phase immediately preceding the cessation of menstruation—occurs on average at age 47.5
- Personal decisions made by women—such as career planning and contraception—as well as stress play a role in individual family planning.
- Consequently, for many women, their first pregnancy occurs at an increasingly later stage in life. The number and quality of eggs decline steadily starting around age 35.
- To ensure the availability of eggs capable of fertilization later in life, women can have their eggs retrieved and frozen (social freezing).
Reasons for men
- Premature infertility in men can result, for example, from excessive alcohol or nicotine consumption, as well as from a severe narrowing of the vas deferens.
- Cancers, such as testicular cancer, are treated by removing the affected testicle. In addition, certain chemotherapy drugs used to treat numerous types of cancer can lead to infertility.
Cryopreservation Procedures
Cryopreservation is a procedure for freezing male or female germ cells or already fertilized eggs.
It is now also possible to harvest fertile ovarian tissue and implant it at a later date. This allows fertility to be preserved, for example, following chemotherapy.
In a subsequent “cryo-cycle,” medical professionals can thaw the cryopreserved cells and use them for in vitro fertilization.
In this process, experts continue to culture the fertilized eggs until they reach the embryonic stage. They then transfer the embryo into the woman’s uterus (embryo transfer). 
Not all cryopreserved eggs are suitable for transfer @ Iryna /AdobeStock
In the case of germ cells (unfertilized), the eggs must first be fertilized with sperm using an IVF or ICSI procedure.
While cryopreservation of male sperm is relatively simple, the preservation of female eggs is more difficult. The reason is the water content of the egg.
Although pregnancy rates following the fertilization of cryopreserved unfertilized eggs are lower than when using freshly retrieved eggs, the vitrification process has significantly improved these outcomes.
Pregnancy Through Cryopreservation
Research into the cryopreservation of germ cells and fertilized eggs is well advanced. In Germany, there are many centers and clinics that offer cryopreservation and promise good results.
Furthermore, there are no known serious adverse effects associated with children conceived through cryopreservation.
The method helps couples in the early stages of family planning and allows for flexibility in timing.
Health insurance plans do not cover the costs of germ cell storage via cryopreservation. Therefore, couples must cover the costs themselves.
Legal Provisions in Germany
The cryopreservation of gametes and fertilized eggs is legal in Germany. If you have gametes thawed and used for artificial insemination, you must submit a written consent form.
In the case of fertilized eggs, a written consent form must be provided by both the woman and the man.
