Vitrification: Pioneering Fertility Preservation
For more than 40 years, sperm has been frozen and thawed and used successfully for in vitro fertilization (IVF). And for about 30 years, embryos have been too. But harvesting and freezing oocytes (unfertilized eggs) has been a challenge, until now.
A rapid freezing process called vitrification is making it possible for women to harvest their eggs and freeze them, unfertilized. And the advantages of the process are enormous.
“Once frozen, these unfertilized eggs remain viable for decades,” said Dr. John Schnorr, medical director of Coastal Fertility in Charleston, South Carolina. “They can be used 20 to 30 years from the date of freezing.”
A medical breakthrough for fertility preservation
For post-pubescent women who have cancer or other conditions that may result in sterility from chemotherapy, vitrification opens a door to one day having genetic offspring with the person they choose down the road.
Here’s what’s so amazing. Say, for example, a 16 year old girl got cancer. Using vitrification, she could harvest and freeze her eggs before undergoing a cancer treatment that could make her sterile. And, when she survived, she’d still be able to have genetic children with her future partner years later.
Plus the process may one day eliminate the pressures of a woman’s biological clock, giving women who want to wait to be moms, the opportunity to use their own youthful eggs to make a baby when they feel the time is right.
How vitrification works
Currently embryos are frozen by first being exposed to cryoprotectants that dehydrates, or removes water, from the cells. Next, the embryos are cooled slowly and then stored in liquid nitrogen. But because individual eggs have increased water content, a zona pellucida and a cytoskeleton they are easily damaged with the freezing process resulting in lower pregnancy rates. ,
But, vitrification prevents this from happening. The process uses higher concentrations of cryoprotectants and much faster cooling rates than traditional freezing methods. The eggs are cooled in tiny straws and freeze at a rate of several thousand degrees per minute. This fast freezing helps to prevent the destructive ice crystals from forming in the egg, so the cells are less likely to burst.
Once vitrified, the egg is stored in liquid nitrogen until it is thawed for fertilization and implantation.
“Currently vitrification is undergoing Institutional Review Board (IRB) approved studies and appears very promising,” Schnorr said. “If studies continue as they have been, it will become mainstay treatment within the next couple years.”Sources