Cell tracking technologies for acute ischemic brain injury.

Stem cell therapy has showed considerable potential in the treatment of stroke over the last decade. In order that these therapies may be optimized, the relative benefits of growth factor release, immunomodulation, and direct tissue replacement by therapeutic stem cells are widely under investigation. Fundamental to the progress of this research are effective imaging techniques that enable cell tracking in vivo. Direct analysis of the benefit of cell therapy includes the study of cell migration, localization, division and/or differentiation, and survival. This review explores the various imaging tools currently used in clinics and laboratories, addressing image resolution, long-term cell monitoring, imaging agents/isotopes, as well as safety and costs associated with each technique. Finally, burgeoning tracking techniques are discussed, with emphasis on multimodal imaging.