According to a report from the UK-based New Scientist (" ëFunctionalí kidneys grown from stem cells", by Claire Ainsworth, 29 January 2002), researchers at Advanced Cell Technology in the U.S. claim to have grown functional bovine kidneys using stem cells taken from cloned cow embryos. The report says the ACT researchers, 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. If confirmed, the work raises the prospect of using stem cells taken from human patients with kidney failure to create new organs for transplant. ACT did not reveal details, and the work has not yet been published in a peer-reviewed journal. As the NS article notes, no details are available as to exactly what these miniature kidneys are, and whether they are in fact complete, functional organs. The kidney is a very complex organ, with an intricate supply of blood vessels that are key to its ability to filter blood.
Additional coverage appeared in the New York Times ("Company Says It Used Cloning to Create New Kidneys for Cow", by K. Chang, 31 January 2002).