HOW TO STOP BIOLOGICAL TIME
Assisted reproductive technology has made great strides since Robert Edwards and Patrick Steptoe pioneered in vitro fertilization. Their technique, which involves taking a woman’s mature oocyte (egg) and fertilizing it with sperm in a petri dish to form an embryo, led to a U.K. woman’s giving birth to the first “test tube baby” in 1978.
The practice of freezing a woman’s eggs started in the 1980s, and the first birth using that method occurred in Singapore in 1986. But slow freezing can damage the female gamete as ice crystals form and squeeze the genetic material. Doctors then started exploring vitrification, a type of flash freezing combined with the use of cryoprotectants that preserves genetic material at minus 196 degrees Celsius without allowing ice formation. The first baby from a vitrified egg was born in 1999, in Italy.
Vitrified eggs have a higher chance of survival than slow-freeze eggs, but the earliest cryoprotectants were often toxic and high survival rates remained elusive. Japanese embryologist Masashige Kuwayama made further advances in cryopreservation while working with bovine and porcine oocytes in 1991. He eventually achieved a 95 percent egg-survival rate.
In 1998, Kuwayama started testing on human oocytes and embryos. The first birth using his method came in 2002 in Japan; the first U.S. birth using it followed in 2003. Kuwayama has continued to refine the procedure, with survival rates now approaching 100 percent. Donor Egg Bank USA and embryologists in 40 countries use it. According to Kuwayama, more than 300,000 children have been born from vitrified oocytes or embryos.