Mesenchymal stem cells engineered to express Neurogenin 1 (MSCs/Ngn1) and the control cells (MSCs/LacZ) cells were labelled with superparamagnetic iron oxide and injected via carotid artery in an acute stroke rat model. T2* magnetic resonance imaging reveals higher engraftment of MSC/Ngn1 than MSC/LacZ up to 25 days (see Kim et al. in this issue, pages 127-141).