T O C

raveling to another country in the hope of finding a stem cell–based treatment for a disease—“stem cell tourism”—has been the object of intense scrutiny in recent years, following reports of charlatanry, baseless claims, and adverse medical events (1). Providers of stem cell–based interventions vary widely in their assertions about the conditions that can be treated, the degree of improvement, and the cell types and protocols used (2), but there are many advertisements for medical procedures that have never been proven efficacious in appropriately designed clinical trials. To date, proven thera-peutic applications for stem cells have been mainly for blood and immunological disorders. The scientific community and ad-vocacy groups have begun to respond by formulating guide-lines for physicians an