Stem cells are increasingly used to treat disorders caused by defective tissues. The repair of blood vessels by vascular endothelial stem cells (VESCs) is an attractive therapeutic option, but the existence of this type of stem cell has not been conclusively shown. Researchers identified a VESC that can regenerate blood vessels and treat a rare bleeding disorder. These VESCs have the potential to serve as a new cell-based therapy for blood vessel-related diseases.