This week's news about researchers growing a new heart from baby cells was exciting, no doubt - a team of researchers from the University of Minnesota, led by Doris Taylor, grew a beating rat heart by adding heart cells from newborn rats to the scaffolding of a dead rat's heart. After only two weeks, the authors report in this month's Nature Medicine, the organ began conducting electrical impulses and pumping blood.

The achievement, researchers said, suggests scientists could one day grow a human heart using stem cells and scaffold from a cadaver. The early success "opens the door to this notion that you can make any organ: kidney, liver, lung, pancreas - you name it and we hope we can make it," Taylor told the New York Times.

Of course, a similar technique has already been tried and tested in humans, using bladders. In December, I reported on a Pennsylvania biotech company, Tengion, that is, as we speak, growing autologous human bladders as part of two phase two trials.