The pluripotent cells that reside in the inner cell mass (ICM) of the early embryo, termed embryonic stem (ES) cells, have the remarkable ability to give rise to the body of the embryo proper. These cells have the unique capability to proliferate indefinitely while retaining an unrestricted developmental potential (Pera, Reubinoff, & Trounson, 2000). Nevertheless, ES cell research is not only ethically and politically controversial but is also limited in capturing the genetic heterogeneity that contributes to human disease (Flake & Zanjani, 1997; Strong, Farrugia, & Rebulla, 2009). So, to investigate the genetic heterogeneity that contributes to human disease is it possible to convert adult cell types into an embryonic state? Forced co-expression of critical transcription factors (TFs) that are turned on in pluripotent cells of the early embryo (Oct4, Sox2, Klf4 and c-Myc) can reprogram somatic cells into self-propagating iPS (induced pluripotent stem) cells (Takahashi & Yamanaka, 2006). The advent of iPS cell lines provided an integral tool for the understanding and elucidation of human neurodevelopmental, neurodegenerative and neuropsychiatric diseases, in a human neuronal context.
