I immediately thought about ice crystals, but the article addresses that:
> Methods have been developed to quickly freeze organs for longer-term storage without risking damage from ice crystal formation, but ice crystals can also form during warming. To address this problem, Yadong Yin and colleagues advanced a technique known as nanowarming, pioneered by collaborator John Bischof, to employ magnetic nanoparticles and magnetic fields to thaw frozen tissues rapidly, evenly and safely.
> Methods have been developed to quickly freeze organs for longer-term storage without risking damage from ice crystal formation, but ice crystals can also form during warming. To address this problem, Yadong Yin and colleagues advanced a technique known as nanowarming, pioneered by collaborator John Bischof, to employ magnetic nanoparticles and magnetic fields to thaw frozen tissues rapidly, evenly and safely.