At Cornell University's lab in Ithaca, New York, a team of researchers has achieved something that could transform how we save embryos—whether to help infertile couples, breed livestock, or rescue endangered species from extinction. They've developed a technique that freezes embryos 30 times faster than current methods, preventing the ice crystal damage that has long plagued cryopreservation and leaving vastly more viable embryos in its wake.
The problem with freezing embryos is deceptively simple but devastating in its consequences. When embryos are frozen using standard protocols, ice crystals form both during the cooling process and again when they're thawed. These ice shards tear through cell membranes, damage proteins, and leave behind genetic scars that ripple through development. Robert Thorne, a physics professor and Stephen H. Weiss Presidential Fellow at Cornell, and his multidisciplinary team realized that if they could speed up the freezing dramatically—borrowing technology from his company MiTeGen, which was developed to preserve crystalline structures for molecular research—they could prevent ice formation altogether.
The research, published in Scientific Reports, focused on bovine embryos, which are notoriously difficult to freeze because of their large size and tendency to form ice. Using the team's ultrafast cooling protocol, the embryos remained ice-free even when the concentration of protective chemicals was reduced by 30 percent. When the embryos were thawed and allowed to develop, something remarkable happened: the fast-cooled embryos behaved almost identically to embryos that had never been frozen at all. They developed far better than embryos frozen using standard methods and successfully resulted in live pregnancies.
The genomic analysis, led by assistant professor Jingyue Ellie Duan, revealed why the difference matters so profoundly. When the team examined which genes were activated after freezing and thawing, they found that embryos frozen at standard speeds showed high expression of genes associated with DNA damage repair—evidence that cells were working overtime to fix injuries. The fast-cooled embryos showed no such distress signal. "There's evidence that all the embryos underwent some kind of stress, but only the group cooled with standard protocols showed that actual DNA damage response," Duan observed.
The implications ripple across multiple fields. For human IVF clinics, the technique could provide more consistent outcomes and better success rates. For livestock breeding, where current freezing methods produce poor results, it could unlock new possibilities for preserving valuable genetic lines. But perhaps most significantly, this breakthrough opens a door for endangered species conservation. Thorne envisions using the method to preserve embryos from species on the brink of extinction, maintaining genetic diversity for future generations. The technique could also serve biomedical researchers who create genetic variants in laboratory animals and need to preserve those carefully engineered stocks.
The work represents a collaboration that stretched across disciplines and, sadly, included the late Soon Hon Cheong, a professor of clinical sciences at Cornell's College of Veterinary Medicine, who played an essential role in choosing the bovine model, producing the embryos, and coordinating the transfers that proved the frozen embryos could develop into living animals. His passing in December 2025 marked a loss to the team, but the results he helped secure suggest a future where freezing embryos—whether for human fertility, animal breeding, or species preservation—need not come at such a costly biological price.