Japan has approved the world's first stem-cell therapy for treating Parkinson's disease. The treatment uses Induced Pluripotent Stem (iPS) cells to replace the dopamine-producing neurons in the brain that are damaged in patients with the disease. iPS cells are adult cells reprogrammed in the laboratory so that they can develop into many other cell types. The approval marks a major step in regenerative medicine, offering a new approach to a progressive neurological disorder that affects movement.