Cryopreservation

Discover the transformative potential of cryopreservation and egg freezing

Cryopreservation is the process of freezing tissue or cells for future preservation. In the context of infertility programs, cryopreservation is commonly used to freeze and store sperm, eggs, or excess embryos from in vitro fertilization cycles. It is particularly beneficial for individuals about to undergo chemotherapy, as it allows them to preserve their reproductive potential.

During puberty, typically around the age of 13 or 14, boys’ testicles begin producing sperm, a process that continues throughout their lives. However, chemotherapy targets rapidly dividing cells in the body, making sperm cells susceptible to damage. If the spermatogonial stem cells, which are responsible for generating new sperm, are severely affected, permanent infertility may occur. To mitigate this risk, it is highly recommended to preserve sperm before undergoing chemotherapy or radiotherapy.

Similarly, cancer treatments can also have detrimental effects on the ovaries in female patients, potentially depleting their ovarian reserve and rendering the ovaries non-functional. Consequently, it is crucial to counsel female cancer patients who have future family-planning aspirations about the option of freezing their eggs prior to commencing cancer treatment. This enables them to preserve their reproductive options and increase the likelihood of future successful pregnancies.

There are 2 methods currently used for freezing in IVF labs.

In IVF (in vitro fertilization) labs, there are several methods commonly used for freezing embryos, sperm, and eggs. The two primary techniques for cryopreservation in IVF labs are slow freezing and vitrification.

Slow Freezing:

Slow freezing is an older method of cryopreservation that involves gradually cooling the cells at a slow rate. Here are the steps involved in the slow freezing process:

Pre-treatment:

The cells are prepared by adding protective substances, such as cryoprotectants, to prevent ice crystal formation and damage during freezing.

Cooling:

The cells are cooled slowly using a controlled-rate freezing machine. This allows the water inside the cells to freeze in a controlled manner.

Storage:

After reaching the desired temperature, the frozen cells are stored in liquid nitrogen (-196°C) to maintain their viability for long-term storage.

Thawing:

When needed, the cells are thawed by rapidly warming them, and the cryoprotectants are removed before use.

Vitrification:

Vitrification is a newer and more widely used method for cryopreservation in IVF labs. It involves rapid freezing, which transforms the cells into a glass-like state without the formation of ice crystals. Here’s an overview of the vitrification process:

Pre-treatment:

Similar to slow freezing, the cells are treated with cryoprotectants to protect them during the freezing process.

Rapid cooling:

The cells are quickly plunged into liquid nitrogen or a specialized freezing solution at an ultra-fast cooling rate. This rapid cooling prevents the formation of ice crystals.

Storage:

Vitrified cells are stored in liquid nitrogen or specialized storage containers, ensuring their long-term preservation.

Warming:

When needed, the vitrified cells are rapidly warmed to their original state by immersing them in a warming solution. The cryoprotectants are removed, and the cells are prepared for use.

Both slow freezing and vitrification have their advantages and disadvantages, and the choice of method depends on various factors such as the type of cells being frozen, the specific IVF lab protocols, and the expertise of the lab personnel. It’s worth noting that vitrification is generally preferred for embryos and oocytes (eggs) due to its higher survival rates and improved post-thaw outcomes.

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