The normal development of the central nervous system (CNS) is a step-wise process: neural stem cells first differentiate into lineage restricted progenitors then mature into terminal functional cell types. However, phenotypic plasticity also exists and neural cells may convert into an earlier cell type that has more differentiation potential or generate cells of other lineages. Cells of non-neural types may also give rise to neural cells upon spontaneous or more controlled cellular process. These events are now collectively termed as transdifferentiation/dedifferentiation or reprogramming, after rule out alternate explanations, such as contaminating populations of cells, revealed competence, and the normal developmental potential of cells. In this chapter, we will present several examples of transdifferentiation in the CNS and how to identify such phenomenon. We will focus on recent advances in controlled reprogramming in CNS, which will facilitate a better understanding of neural development and differentiation mechanisms, including transcriptional network regulation and posttranscriptional modification. In addition, we will discuss potential clinical relevance of transdifferentiation/dedifferentiation in the CNS with implications of future regenerative medicine in treating neurodegenerative diseases, neural developmental diseases, and cancers.
