Vitrification, or rapid freezing of embryos and gametes

Q: Safeguarding fertility

Fertility preservation in the face of disease or very low ovarian reserve (AMH) It is common practice to preserve the gametes of patients when an existing and progressive disease, e.g. cancer, and therefore the implemented therapy that the patient must undergo, threatens to damage the function of the gonads and reproductive cells, leading to fertility problems in the future. This treatment is called fertility preservation. Find out more about fertility preservation >>.

Q: Material banking

Storage of biological material in a donor bank. Cryopreservation secures material deposited by anonymous donors who donate their reproductive cells (sperm and ova) to individuals who are incapable of producing their own gametes or whose reproductive functions are impaired to the extent that the processes leading to normal embryos, pregnancy and offspring are not possible.

Vitrification is a cryopreservation technique for gametes and embryos. It is the preservation of biological material at extremely low temperatures. Vitrification is also known as vitrification. It differs from freezing in liquid nitrogen in that, thanks to the use of special cryoprotectants, it does not lead to the precipitation of ice crystals that could damage the cells.

In recent years, techniques have emerged in the treatment of infertility by assisted reproduction methods (ART) that have revolutionised treatment and contributed to their increased effectiveness and the birth of millions of children worldwide. In addition to ICSI (the intra-cytoplasmic insertion of a sperm into an egg), a method that is a milestone in the development of assisted reproductive techniques, is the technique of cryopreservation of gametes (sperm and ova) and embryos called vitrification.

Embryological consultation

If additional questions come to mind after reading this article, remember that all Invimed patients qualified for insemination or IVF can benefit from the free embryological consultation.

What is cryopreservation?

Cryopreservation (cryopreservation) techniques, i.e. the effective preservation of biological material at low and extremely low temperatures, are an integral part of in vitro fertilisation (IVF) treatment, and the ongoing development and increasing effectiveness of the method, mean that the importance of cryopreservation in treatment cycles continues to increase.

Cryopreservation techniques are used to protect:

diagnostic semen testing including:
- computer-assisted semen analysis (CASA),
- sperm DNA fragmentation testing (SCD),
- testing the degree of sperm binding to hyaluronan (HBA),
- morphology study of motile sperm organelles (MSOME),
isolation of oocytes from material obtained by the doctor during the puncture of ovarian follicles,
morphological assessment of oocyte quality and the Oosight polarised imaging system,
preparation of ova for IVF procedures,
evaluation and preparation of semen for insemination and in vitro fertilisation procedures,
performing in vitro fertilisation procedures, i.e. IVM, IVF, ICSI/PICSI/IMSI/HBIMSI (read the article: In vitro fertilisation methods).
embryo culture to the blastocyst stage (IVC),
performing embryo biopsies for pre-implantation genetic testing of PGT-A and PGT-M (read article: Genetic diagnosis),
standard monitoring of embryo development, assessment of their development and implantation potential,
Time Lapse Imaging monitoring of embryo development and prediction of developmental potential,
preparing embryos for transfer,
freezing, storage and thawing of semen and ovarian tissue,
Vitrification and heating of oocytes and embryos (read article: Vitrification),
running a germ cell and embryo bank.

Free embryology consultations at Invimed

Invimed patients can benefit from an embryology consultation from the moment they have started preparing for assisted reproductive procedures at their chosen Invimed clinic. A consultation with an embryologist does not have to be ordered by the attending physician, but may be recommended by him or her.

Embryology consultations are directed to Invimed patients who are interested in:

Embryological procedures and their effectiveness at Invimed.
The course of the embryological procedure in their case and its outcome concerning, for example, the number of embryos obtained and vitrified, the quality of oocytes, sperm and embryos.
Interpretation of own test results of comprehensive semen testing, SCD, MSOME, HBA and about methods to determine oocyte and embryo quality.
Assisted reproduction procedures used at Invimed and their effectiveness (insemination, standard IVF, ICSI, IMSI, PICSI, hb- IMSI, ED, sperm freezing, oocyte and embryo vitrification, preimplantation genetic testing).
Topics related to embryology that patients think may apply to their treatment process at Invimed.
Possible reasons for failure, lying in the field of embryology (for patients who did not achieve pregnancy through the procedure or who had a miscarriage after confirmation).

Further treatment

A chance for further treatment or another child in the family.
Both cryopreserved gametes (spermatozoa and ova) and embryos can be used for further treatment if the first attempt is unsuccessful, as well as for success when patients express a desire to expand their family with another member.

Safeguarding fertility

Securing fertility in the face of disease or very low ovarian reserve (AMH)
It is common practice to preserve the gametes of patients when an existing and progressive disease, e.g. cancer, and the consequent therapy the patient has to undergo, threatens to damage the function of the gonads and reproductive cells, leading to fertility problems in the future. This treatment is called fertility preservation.
Find out more about fertility preservation >>

Material banking

Storage of biological material in the donor bank.
Cryopreservation secures material deposited by anonymous donors who donate their reproductive cells (sperm and ova) to individuals who are incapable of producing their own gametes or whose reproductive functions are impaired to the extent that the processes leading to normal embryos, pregnancies and offspring are prevented.

Slow freezing of gametes and embryos

Until recently, cryopreservation of gametes and embryos was routinely carried out using what is known as 'slow freezing', a protocol that has been well known and recognised by clinical and academic centres for years. However, as this method was fraught with several imperfections, thanks to numerous studies, scientists have managed to develop a better method, vitrification.

Among the shortcomings of slow freezing are:

high probability of ice formation inside the cell, or in its immediate vicinity, which contributes to cell damage.
Insufficient protection of biological functions during slow cooling of the sample. In many cases, although the cells survived the process, many of them did not undertake further development after thawing.

Vitrification as a better form of freezing (cryopreservation)

The risks of ice crystal formation and impaired biological functions described above were reduced by rapid cooling of the biomaterial to low temperatures, i.e. vitrification.

What is vitrification?

Vitrification involves immediately bringing the temperature of the cryoprotectant solution containing the cells or embryos down to -196˚C, the temperature of liquid nitrogen. During this process, also known as vitrification (vitrum from the Latin, means glass) in the solution surrounding the cell, as well as in the cell itself, no ice crystals are produced.

Rapid exposure of biological material, protected by suitably high concentrations of cryoprotentants, to extremely low temperatures prevents the formation of a solid, i.e. ice crystals. The solution vitrified with the biomaterial, although resembling a solid (glass) in its properties, physically remains a very dense liquid.

Biological materials that can be vitrified avoid intracellular damage and other detrimental effects of slow cooling on cell biology.

Vitrification - the most effective embryo protection

Performed correctly and standardised, vitrification is currently the safest and most effective form of cryopreservation.

Thanks to the implementation of vitrification in clinical practice, IVF has become extremely effective and the results obtained with it would have been unthinkable a dozen years ago.

In the event of failure of fresh embryo transfer, the use of vitrification-protected surplus embryos created during the IVF procedure ensures a survival rate of 99%. After thawing (warming) they undertake further normal development.

For embryos that have previously been cryoprotected by vitrification, the chances of achieving a pregnancy and giving birth to a healthy baby are identical to the clinical results obtained with 'fresh' (non-cryopreserved) embryos.

The situation is similar with vitrified oocytes, the use of which provides results characteristic of cells that have not been cryopreserved.

Why is freezing embryos and oocytes a difficult process?

Both embryos and oocytes themselves (the cells that give rise to egg cells) are very specific material and their cryopreservation is challenging. Their cryopreservation is difficult due to their size, shape, the additional barrier that is the transparent envelope and their biological specificity (metabolism and developmental status).

All these features mean that the successful translation of cryobiology principles operating within other fields of medicine and biology is not straightforward or obvious when applied to reproductive medicine. For this reason, the invention of vitrification is an achievement comparable to the development of a method of ICSI (the intra-cytoplasmic insertion of the sperm into the egg).

Why are sperm frozen and not vitrified?

The vitrification procedure is not normally used to store sperm (semen) for use in ART procedures. The specific structure of the sperm and the conditions necessary for vitrification (rapid cooling rate, minimum volume of cryoprotectant, high concentration of cryoprotectant - much higher than for freezing, and special media for the sperm) limit the validity of its use to only certain cases. Vitrification of single spermatozoa or spermatids obtained from testicular biopsies, for example, is possible. In other cases, the spermatozoa are subjected to slow freezing in liquid nitrogen vapour. This is the safest cryopreservation method for them.

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