Organs need to be transplanted very quickly, since they soon deteriorate when deprived of oxygen. The normal procedure is to cool them to prevent this deterioration, though this freezing may itself cause damage. Surgeons in London have recently achieved a first: the transplant of a 'warm' liver.
Here, the liver was kept alive, and at body temperature, artificially, being supplied with oxygenated blood and nutrients. This allows the liver to be preserved for up to 24 hours, rather than having to be transplanted within 10-12 hours: so speed is still important, but this is a considerable increase in the timeframe.