These preliminary findings suggest that the pace of functional maturation is influenced by the local environment, though the corresponding mechanisms remain to be determined. While it is possible that species-specific maturation rates trigger the timing of cortical interneuron maturation (e.g. by regulating activity), it is also possible that there are simply more astrocytes in mouse versus human feeders (Johnson et al., 2007). Future studies should include co-culture with primary cortical neurons of human embryonic origin to further corroborate our findings. Independent of the mechanism, our data demonstrate that the mouse co-culture conditions enhance maturation of hESC-derived cortical interneurons and enable functional in vitro studies.
