Stroke and traumatic brain injury lead to cell death characterized by a loss of neurons and oligodendrocytes within the brain. Healthy adult brains contain neural stem cells that divide, and act to maintain stem cells numbers or become progenitor cells. In healthy adult animals, progenitor cells migrate within the brain and function primarily to maintain neuron populations for olfaction (the sense of smell). Interestingly, in pregnancy and after injury this system appears to be regulated by growth factors and can increase the rate at which new brain matter is formed. In the case of brain injury, although the reparative process appears to initiate, substantial recovery is rarely observed in adults suggesting a lack of robustness. Recently, results from research conducted in rats subjected to stroke suggested that administration of drugs to increase the stem cell division rate and direct the survival and differentiation of newly formed cells could be successful. In the study referenced below, biological drugs were administered after stroke to activate two key steps in the reparative process. Findings from this study seem to support a new strategy for the treatment of stroke using a simple elegant approach aimed at directing recovery from stroke by potentially protecting and/or regenerating new tissue. The authors found that, within weeks, recovery of brain structure is accompanied by recovery of lost limb function suggesting the potential for development of a new class of stroke therapy or brain injury therapy in humans