In an ‘historic’ first, scientists freeze, thaw, and transplant rat organs — bringing transplant medicine one step closer to sci-fi dreams of stopping biological time.

In all, five rats received a vitrified-then-thawed kidney in a study whose results were published this month in Nature Communications. It’s the first time scientists have shown it’s possible to successfully and repeatedly transplant a life-sustaining mammalian organ after it has been rewarmed from this icy metabolic arrest.