Adult neurogenesis from reprogrammed astrocytes.

The details of adult neurogenesis, including environmental triggers, region specificity, and species homology remain an area of intense investigation. Slowing or halting age-related cognitive dysfunction, or restoring neurons lost to disease or injury represent just a fraction of potential therapeutic applications. New neurons can derive from stem cells, pluripotent neural progenitor cells, or non-neuronal glial cells, such as astrocytes. Astrocytes must be epigenetically "reprogrammed" to become neurons, which can occur both naturally in vivo, and via artificial exogenous treatments. While neural progenitor cells are localized to a few neurogenic zones in the adult brain, astrocytes populate almost every brain structure. In this review, we will summarize recent research into neurogenesis that arises from conversion of post-mitotic astrocytes, detail the genetic and epigenetic pathways that regulate this process, and discuss the possible clinical relevance in supplementing stem-cell neurogenic therapies.