Preclinical validation of fast oocyte vitrification and warming protocols with comparable efficiencies to a standard method
Costa-Borges et al., 2025
When eggs (oocytes) need to be frozen for fertility preservation, they must be exposed to special protective chemicals called cryoprotectants before being plunged into liquid nitrogen. Current protocols require eggs to spend about 15 minutes gradually adjusting to these chemicals, but this prolonged exposure at room temperature may harm the eggs. This study tested whether dramatically shortening these exposure times - to just one minute - would still protect eggs effectively. Using mouse and rabbit eggs as models, researchers compared the fast protocol to standard methods by examining egg survival, internal structures (especially the spindle that holds chromosomes), fertilization success, and embryo development. The fast protocol performed just as well as the standard method in all tests. Mouse embryos created from fast-frozen eggs developed into healthy adult mice at similar rates to controls. The team also created a computer model to predict how human eggs would behave with the fast protocol, then validated these predictions using donated human eggs. These findings suggest that the time-saving fast protocol could improve laboratory efficiency and potentially egg quality by minimizing exposure to suboptimal conditions.