Almost two decades ago, William Frey, director of the Alzheimer's Research Center at what is now Regions Hospital, in St. Paul, Minnesota, showed that it is possible to use an intranasal route to deliver therapeutic proteins directly to the brain. More recently, he and Lusine Danielyan tested whether this route could be used for cells. In experiments done in Danielyan's lab at the University Hospital of Tuebingen, the researchers administered fluorescently labeled mesenchymal stem cells or human glioma cells to the upper nasal cavity of adult mice or young rats, respectively. They observed a measurable number (hundreds to thousands) of labeled cells in the olfactory bulb, the hippocampus, the thalamus and the cerebral cortex within an hour after administration of 3 × 105 cells.