Cryopreservation: Zemya IVF

• Since at -196°C in the presence of liquid nitrogen, there is a complete cessation of metabolism in cells, it becomes possible to store the cells for a long time without any harm to their structure or function.
• In terms of flash freezing, it completely prevents the formation of crystals of ice within the cells.
• Thus, by storing the cells in such an environment, they are protected from any genetic changes or mutations.
• From either a lifestyle point of view or even a medical one, cryopreservation becomes a very important step for anyone to take.

Pausing biological time is quite revolutionary in the fields of advanced medicine, reproductive sciences, and biotechnology. Cryopreservation, a method of storage for the long-term at ultra-low temperatures, lies at the core of this technique. It preserves the morphological and genetic features of living cells, tissues, and biological substances. Essentially, this method stops all metabolic processes and cell proliferation, so complex living systems can be preserved safely for a long time.

For Zemya IVF & Fertility Clinics, which holds the prestigious title of the Best IVF Centre in Delhi, cryopreservation is the cornerstone that lays the foundation of our lab facilities. It may be for the purpose of preserving fertility, cryopreservation of preimplantation embryos, or storage of rare genetic material, but knowledge of the scientific principle of freezing cells makes patients realize how safe the process is.

The Fundamental Science Behind Cryopreservation

The main problem with cooling live organisms down to ultra low temperatures is that the cells can get damaged. When we expose whole cells, tissues, or even a suspension of cells to cold temperatures, the water inside as well as in the surroundings freezes since the temperature is below the freezing point of the water. Ice crystals start forming very quickly in such case if no precautions are taken.

• Ice behaves in different ways when it starts freezing, depending on how fast the cooling process occurs:
• Extracellular Ice Formation: As soon as cooling starts, ice forms outside the cell membrane. In this case, the concentration of salts outside the cell increases, which causes an influx of water from the cell through osmosis.
• Freezing inside Cells: At the stage where the rate of cooling is excessive and there are no protective substances to stop this process, lethal ice crystal formation occurs inside the cells, causing damage to the cell membrane.To avoid cell damage from physical trauma and changes in temperature, scientists use CPA combined with a special freezing medium. These chemical agents lower the freezing point inside cells, reduce cellular dehydration, and help to avoid deadly ice formation. This combination of features leads to better cell viability after thawing.

Two Main Cryopreservation Techniques

Based on the biological samples involved in freezing such as mammalian cells, CHO cells, fowl sperm, or difficult seeds, there are varied techniques employed by embryologists in order to overcome the phase transition.

1. Slow Freezing

In this age-old method, a slow cooling rate (usually about 1 °C per minute) is applied inside a programmable machine. A small amount of cryoprotective agents is being used. With this controlled, slow freezing rate the water leaves the cell in an orderly manner thereby minimizing internal ice formation. Although good for particular tissue matrices, it needs careful checking so as not to have a toxic buildup of solutes.

2. Vitrification (Ultra-Rapid Flash Freezing)

The current industry norm for freezing embryos during IVF is vitrification. During vitrification, the freezing process completely skips the step of crystals being formed since the temperature falls so fast due to a high amount of CPAs. In this process, the liquid turns into glass and there is no harm done to the cells at all.

Applications

Cryopreservation, despite its strong associations with fertility treatment, can be employed in a broad spectrum of critical fields:

• Reproductive Medicine: To provide individuals with the ability to defer conception through the preservation of their sperm, eggs, embryos, ovarian, and testicular tissues.
• Stem Cells and Gene Therapy: Freezing totally pure stem cells and special biological materials for regenerating therapy cells and for gene therapy advancements.
• Molecular Biology and Research: Preserving different cell cultures, important stains, and complicated cell lines in the log stage before they go extinct due to any genetic shift or genetic contamination
• Conservation Ecology: Preserving genetic templates of rare species and plants for unexpected extinction or loss of biodiversity
• Agriscience and Food Science: Used in plant physiology to conserve seed stocks and germplasms in food science.

Storage In Liquid Nitrogen: The Sub-Zero Standard

When the complex freezing method is complete, the frozen samples are rapidly shifted to storage containers meant for long-term preservation. To keep them securely, we require an environment much colder than a regular freezer or dry ice.

Cells are stored submerged in, or just above, the liquid nitrogen level, where the environment is so stable that it is kept at a permanent -196 °C. At these frigid temperatures, all chemical, thermal, and kinetic reactions are frozen. Stable in these top-of-the-range tanks, cells can, in principle, live for hundreds of years without deteriorating or rotting away and are totally protected from outside influences as well as microorganisms.

Maximizing Cell Viability Post-Thaw

Yes, the very measure of success for any cryopreservation scheme is the cell survival rate after the next freezing and thawing cycle. The thawing part needs a very fast warming up so that ice doesn’t get a chance to recrystallize, and the sample changes back to room temperature.

Our state-of-the-art clean room facilities at Zemya IVF & Fertility Clinics are equipped with superior vitrification solutions, as well as optimal warming techniques. This guarantees that upon the thawing process of an embryo or gamete, its cellular integrity and metabolic capabilities are restored, thus giving it similar capabilities to fresh specimens.