The advent of stem cell biology has opened new avenues in the field of neuroscience research as well as therapeutic approaches for neurological diseases. Although it is clear that human pluripotent stem cells (hPSCs; i.e., both human embryonic stem cells [hESCs] and human induced pluripotent stem cells [hiPSCs]) can give rise to functional neurons, a current challenge is to develop differentiation strategies that can produce disease-relevant subtypes of neurons. To date, progress has been made to generate enriched populations of ventral midbrain dopaminergic neurons and spinal motor neurons to model Parkinson disease and amyotrophic lateral sclerosis, respectively (Perrier et al., 2004; Roy et al., 2006; Di Giorgio et al., 2008; Dimos et al., 2008; Marchetto et al., 2008; Kriks et al., 2011; Ma et al., 2011). In addition, cortical pyramidal neurons and forebrain interneurons have been generated from hiPSCs (Shi et al., 2012a,b; Vanderhaeghen, 2012; Maroof et al., 2013; Nicholas et al., 2013). Most of these methods induce differentiation that approximates the in vivo developmental program. Consequently, in addition to producing a neuronal subtype, hPSCs can potentially recapitulate the developmental
