From BusinessWeek: "Patients blinded in one or both eyes by chemical burns regained their vision after healthy stem cells were extracted from their eyes and reimplanted ... The tissue was drawn from the limbus, an area at the junction of the cornea and white part of the eye. It was grown on a fibrous tissue, then layered onto the damaged eyes. The cells grew into healthy corneal tissue, transforming disfigured, opaque eyes into functioning ones with normal appearance and color ... The stem-cell treatment restored sight to more than three-quarters of the 112 patients treated. ... The key to success is to be certain that when the stem cells extracted from the limbus are grown in culture they have the right mix of stem cells and the differentiated cells that form the corneal tissue ... If there are too few stem cells in the transplant, the improvement won't last because there will be no reservoir to form the new corneal cells needed with the normal recycling of cells over time. ... Depending on the depth of the injury, some patients regained sight in as little as two months. ... Others with deeper injuries needed a second procedure and waited a year before sight was restored."