US scientists claim to have grown functional kidneys using stem cells taken from cloned cow embryos.Robert Lanza of biotech company Advanced Cell Technology told New Scientist that his team, working in collaboration with a group at Harvard University, coaxed the stem cells into becoming kidney cells, and then “grew” them on a kidney-shaped scaffold.

The two-inch-long mini-kidneys were then transplanted back into genetically identical cows, where they started making urine, Lanza says.