MGE cells spontaneously differentiate into Lhx6- and Sox6-expressing GABAergic interneurons, indicating that they are phenotype-specified neural progenitors with intrinsic properties to become specific subtypes of GABAergic interneurons. CGE cells generated VIP+ and Calretinin+ neurons, again demonstrating their developmental potential. However, within the time frame of this study, there were still many interneurons that did not show mature marker expressions, such as Somatostatin or Parvalbumin. Previous studies have reported that such markers are expressed in the long-term maturation process of human interneurons that follow their internal clock during the course of human brain development [18,38]. This long-term maturation could pose a major problem for downstream application that requires mature interneurons. However, such early developing interneurons before full maturation exhibit great potential for cell replacement therapy with their migratory function and ability to integrate into adult brains [39]. Additionally, they are more amenable to cell culture manipulations, such as trypsinization, compared to mature cortical interneurons with elaborate branching patterns. In fact, we have shown that these maturing interneurons demonstrate efficacy in ameliorating seizure activity even before attaining full maturation [29]. These developmental
