June 17, 2012
On June 17, 1972, Mazur and his colleagues celebrated the birth of the first mammals from early embryos that had been frozen to -321 degrees Fahrenheit in their cryogenic research lab and thawed for implantation into a foster mother. The newborn mouse pups made the cover of Science magazine four months later, when the research results were published, and Mazur and his Oak Ridge National Laboratory research partner, Stanley Leibo, and British collaborator David Whittingham were the toast of the biology community and beyond.
Successfully freezing and thawing embryos was an extraordinarily delicate procedure that had generally been met with failure by cryobiologists who’d theorized about the best techniques and experimented with various solutions to preserve the embyroys and prevent the formation of ice — a lethal flaw — during the process. . . .
The 84-year-old scientist, a research professor at the University of Tennessee for the past 13 years, walked at a brisk gait earlier this week as he showed me and a photographer to his office — jammed with volumes of research papers, his own and others — and shared some diagrams and descriptions of those 1970s experiments and reprint of the Oct. 27, 1972 issue of Science.
“It was a big deal,” Mazur said, recalling the excitement of the time. . . .
Mazur noted that six years after their paper was published in Science, Patrick Steptoe and Robert Edwards reported in the medical journal Lancet the birth of a child resulting from in vitro fertilization of a human oocyte (unfertilized egg). Edwards was awarded the 2011 Nobel Prize in Physiology or Medicine for that work.
“The combination of procedures of IVF, embryo transfer and embryo cryopreservation has led to an explosion in the use of assisted reproduction applied to humans as well as to laboratory, and domestic and wild animals,” Mazur wrote.
According to stats provided by Leibo, in the past 20 years there have been at least 2 million live calves born all the world from cryopreserved cattle embryos. The same procedure has also been used to preserve embryos of at least 25 other mammalian species.
In the case of humans, from 2005 to 2009 in the United States, more than 37,000 pregnancies were produced by transfer of cryopreserved human embryos.
Now we take that stuff for granted.