From the Technology Review: "Our joints are one of the first body parts to suffer the inevitable ravages of aging: cartilage may be torn in overzealous basketball games or slowly worn away over years of use. Scientists are now experimenting with a combination of stem cells and novel scaffold materials designed to mimic real tissue, in hopes of permanently vanquishing the pain that accompanies this damage and perhaps preventing the onset of arthritis. In animal models, these transplants appear to spur regeneration of cartilage that better resembles native tissue. ... In a recent pilot experiment in pigs, researchers sutured the cell-laden scaffolds over damaged cartilage in the animals' knees. Six months later, new tissue had formed, with a smooth surface and mechanical properties similar to those of native cartilage. The tissue also expressed molecular markers characteristic of normal cartilage. ... he aims to begin human tests in the next two years. First, his team must do additional studies in large animals, such as goats or sheep, over a longer period of time, to make sure that the treatment is safe and effective."