PRNP and Stroke: Neurogenesis and angiogenesis are closely linked in the ischemic brain, newly formed vessels providing guidelines for NPCs on their way to the stroke lesion.6 Newly formed blood vessels and NPCs mutually stimulate each other via release of trophic factors and guidance molecules.6, 8, 35 Neurogenesis and angiogenesis were increased both in ischemic PrP+/+ and in PrP−/− mice.