Cryopreservation is a process that cools samples of organelles, cells, tissues, or other biological constructs to very low temperatures for preservation. By using very low temperatures, cryopreservation keeps living cells and tissues structurally intact.
Cryopreservation is different from unprotected freezing, which is typically lethal. Freezing injury is caused by both direct damage from ice crystals and secondary damage from the increase in the concentration of solutes as more ice is formed.
Cryopreservation provides stable conditions to preserve life, typically through the use of cryoprotectants.
There are four general types of cryopreservation processes: (1) slow freezing, (2) vitrification or ultra-rapid cooling, (3) subzero nonfreezing storage (preservation via a variable magnetic field without the use of cryoprotectants), and (4) preservation in the dry state (a preservation method still being perfected that would better facilitate the commercialization of cell-based therapies).
Benefits of Cryopreservation
The preservation/extended storage times of stem cells and other viable tissues are extremely useful for research and medical applications, including (1) cryopreservation of cells/organs; (2) cryosurgery; (3) biochemistry and molecular biology; (4) food sciences; (5) ecology and plant physiology; and (6) medical applications, such as blood transfusion, bone marrow transplantation, artificial insemination, and in vitro fertilization (IVF).
Further, the long-term storage of stem cells is a preliminary step in tissue engineering and regeneration, which offers hope for diseases with no current treatments.
An embryo is a fertilized egg. Embryo freezing uses cryopreservation to freeze and store embryos for later use. Embryo freezing typically follows in vitro fertilization (IVF) treatments, which sometimes result in extra embryos. Freezing embryos gives users the option to pursue fertility treatments later. Embryo freezing is also an option for a woman who may want to pursue fertility at a later time, such as after cancer treatments.
Sperm cryopreservation is an option for fertility preservation for men being treated for cancer and for couples experiencing infertility. Sperm freezing is also emerging as an element of gender reassignment therapy.
Ovarian Tissue Cryopreservation
The process of freezing ovarian tissue for fertility preservation is relatively new; the process was considered experimental until 2019. Ovarian tissue cryopreservation removes the ovarian cortex, or the egg-producing portion of the ovary, freezing it until years later when it can be used to make pregnancy possible. Ovarian tissue preservation can also help to restore hormone production, which can suffer because of damage to the ovaries. Ovarian tissue cryopreservation is an option for women and girls who plan to undergo cancer treatment or gender affirmation surgery.
Egg freezing costs between $15,000 to $20,000 on average per cycle. Most women pursue two cycles, driving the cost of egg freezing to between $30,000 and $40,000 for treatment and storage. Sperm freezing and storage costs roughly $1,000 or less the first year and then a lesser cost each following year. The cost of ovarian tissue freezing and storage varies.