evidence of significant or durable functional improvement (Cicchetti et al., 2009). Thus, the specific generation of midbrain dopaminergic neurons and medium spiny neurons from human embryonic stem cells and iPSCs (An et al., 2012; Carri et al., 2013; HDConsortium, 2012; Kriks et al., 2011; Roy et al., 2006), by providing defined populations of neurons of relative phenotypic homogeneity, has enabled a leap forward in the design and therapeutic potential of cell transplantation for each of these disorders (Thompson and Bjorklund, 2015).
