FROZEN EMBRYOS SHIFT THE FUTURE OF FAMILIES

By Ashley Chen Emory Kim

Born from a 27-year-old embryo, Molly Gibson breaks her sister’s record for the longest-frozen embryo to result in a live birth. Her unique story brings a new meaning to the term “old soul.”

On October 14, 1992, weeks before Bill Clinton was elected for president, an embryo was frozen. In February 2020, as the COVID-19 pandemic had begun to take hold, that embryo was thawed and transferred to the uterus of 28-year-old Tina Gibson, a Tennessee woman who had struggled to start a family with her husband, Ben.

On October 26, 2020, along came Molly—a 6-pound, 13-ounce baby girl—breaking the record for the longest frozen embryo to have resulted in the birth of a child. The previous record-holder, the embryo that created her sister, Emma, had been frozen for more than 24 years. Both baby girls were frozen together as embryos that were donated by the same couple, making the girls full genetic siblings.

Like many other families who turn toward donor embryos, the Gibsons did so due to their fear of passing a genetic disorder onto their offspring. Ben has cystic fibrosis and Tina is a carrier. Cystic fibrosis (CF) is a genetic disorder that alters the way the body produces mucus; mucus aids in the function of organs and systems and should be thin and slippery. However, in the case of CF, mucus becomes thick and sticky, blocking tubes and ducts throughout the body. Their unique story opens the door for a better understanding of assisted reproductive technology (ART) as well as challenges conventions for future generations of children, families, and embryos.

Embryo donation stems from the process of in vitro fertilization (IVF), a type of assisted reproductive technology. IVF helps people with infertility who want to have a baby as well as parents who run the risk of passing a genetic disorder onto their offspring.

Infertility encompasses women who are unable to conceive after one year of trying. Often brushed under the rug, infertility is a serious issue that affects about 6% of married women aged 15 to 44 years in the U.S. In fact, 2% of all births in the U.S. now result from ART—indicating that births via ART have skyrocketed more than threefold since 1996.

In vitro fertilization involves retrieving eggs from a woman’s ovaries and fertilizing them with sperm. The fertilized egg, or embryo, can then be frozen for storage or transferred to a woman’s uterus. According to Dr. Sigal Klipstein, “once an embryo is frozen, it stays at the same level of development forever.”

There are two different ways in which embryos can be frozen: slow freeze and vitrification. Slow freezing involves cooling the cell very slowly—at a decrease of roughly 1 Celsius per minute—until the final storing temperature of -196 ℃ is reached. The entire process spans over a couple of hours. Over time, slow freezing has become less prevalent, as embryos undergoing the slow freeze technique are less likely to survive the thaw, giving rise to the popularity of vitrification. Indeed, according to Valojerdi and his coworkers (2009), vitrification provides “a higher survival rate of human embryos and minimal deleterious effects on post-warming embryo morphology.” As it turns out, speed plays a crucial role in the success of egg freezing. The longer

the freezing process takes, the more likely it is that ice crystals will form in the cell, increasing the risk of cell structure damage and reduction in cell functionality. Luckily, biologist Dr. Masashige Kuwayama and others developed breakthrough vitrification protocols in the early 2000s. While the slow freezing technique takes hours, vitrification is completed in minutes. Vitrification, or flash freezing, is a method that cools cells so quickly to -196 ℃ that they become vitrified—glass-like.

To paint a more concrete picture of the process, the Gibson embryo was frozen and left in a deep freeze in liquid nitrogen for many years. Similarly, frozen embryos can be transferred back to the person who produced the egg or to another person. Regardless of how long an embryo has been frozen, it can be thawed and transferred, as the potential to become a pregnancy does not decline as a result of being frozen.

With the currently available and highly developed assisted reproductive technology, the future of frozen embryos shines bright. The Gibsons challenge the boundaries of donor embryos, prompting scientists to engage in a broader discussion about the protection of embryos frozen in storage.

In fact, a large number of embryos in frozen storage present a practical issue for private clinics in addition to medical centers as keeping track of embryos harbors difficulties. However, while Gibsons’ story provides unprecedented exposure to in vitro fertilization and frozen embryos, their story may eventually become the convention. According to Omurtag, “as more and more embryos are frozen, it will not be unusual for couples seeking embryo donation to use embryos that were stored in 2010 and to use them in 2040.” Indeed, the Gibsons give hope to others who undergo IVF as well as those who are considering using frozen embryos—combating the issue of infertility and lowering the risk of the inheritance of genetic disorders.

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