Glassy life
Vitrification will help to preserve embryos for centuries
A long-standing dream of science fiction writers has come true. Modern science is already able to freeze people and store them for centuries. However, so far it is possible to cryopreservate a person only at the embryo stage. For this purpose, the so–called vitrification is used - ultrafast freezing using a special cryoprotective solution. Under the action of this solution, the embryo turns into a vitreous state. Vitrification guarantees almost one hundred percent survival of embryos.
Eggs and spermatozoa can also be frozen by a similar method. Depending on the problem, the desired biological object is selected. Oksana Struikhina, clinical embryologist, PhD, explains: "Eggs and embryos up to the stage of 6-8 blastomeres contain a larger volume of intracellular fluid, therefore they are more sensitive to freezing. A 5-6-day-old embryo (blastocyst) has smaller cells and less intracellular fluid, so it is easier to tolerate freezing and defrosting."
The number of women who decide to use such "insurance for late pregnancy" is growing over the years. Cryopreservation of their own eggs is decided by many ordinary women around the world, as well as well–known stars - from Alla Pugacheva to Celine Dion. Some employers even include cryopreservation among corporate benefits – along with standard medical diagnostic procedures. In general, the simplest principle remains appropriate for freezing – "the earlier, the better."
How is the freezing and thawing of embryos? A special substance is added to them – a cryoprotector that prevents damage during freezing. Then the embryos are placed in a specially labeled straw. Then they are cooled to extremely low temperatures. In this state, the embryos look like small balls placed in liquid nitrogen at a temperature of -196 ° C. After extraction from liquid nitrogen, the cryopreserv is gradually thawed at room temperature, and the cryoprotector is removed. Vitrification, on the other hand, involves an ultrafast transition of the liquid with the cryoprotector immediately into a glassy state. Embryos on a small plastic spatula are immersed in a straw holder, frozen in liquid nitrogen in literally ten to fifteen minutes - and thawed just as quickly.
Embryo vitrification procedure (neo-clinic.com )
What is the shelf life of frozen "cryopreservation"? Liquid nitrogen at such a low temperature completely stops the metabolic activity of cells, and embryos can be stored, in fact, "on demand" – even for decades (a frozen egg has a lower shelf life – up to ten years). The key factor here remains the legal factor: that is, timely contact of patients with the clinic. During the paid storage period, they choose whether to continue storing the embryos at the end of this period, transfer them to the uterus, dispose of them, or, for example, donate them for scientific research.
And sometimes it is not without resonant legal processes. For example, in 2016, an unprecedented trial between two spouses who did not share embryos during the divorce became famous throughout Russia.
The price of vitrification turns out to be lower than carrying out a new IVF cycle: storing eggs or embryos costs about a couple of tens of thousands of rubles a year, and IVF is already a couple of hundred thousand.
"Embryo cryopreservation is a very gentle procedure for the patient. If a woman fails to give birth in the intended cycle or she wants to give birth to another child, then ready-made embryos can save her from stimulation with huge doses of hormones. Being recently developed, vitrification now occupies a dominant position in the field of embryologists. Doing without a software freezer, it turns out to be very cheap and is used very often – as a rule, all embryologists working in the clinic are able to do it. There is no special alternative to replace vitrification yet," notes M. L. Semenova, Doctor of Biological Sciences, Professor of the Department of Embryology, Faculty of Biology, Lomonosov Moscow State University.
Many (for example, Susan Bewley, a professor at King's College London) believe that soon the majority of young girls who are favored by financial circumstances will use cryopreservation. Perhaps someday it will become a new "rubicon of maturity" for women and will become one of the traditional rituals - like ear piercing.
Portal "Eternal youth" http://vechnayamolodost.ru
18.05.2017