Parkinson disease (PD) is caused by the progressive degeneration of brain cells known as dopamine (DA) cells. Replacing these cells is considered a promising therapeutic strategy. Although DA cell–replacement therapy by transplantation of human fetal mesencephalic tissue has shown promise in clinical trials, limited tissue availability means that other sources of these cells are needed. Now, Ernest Arenas and colleagues at the Karolinska Institue, Sweden, have identified a new source for DA cells that provided marked benefit when transplanted into mice with a PD-like disease.
