Generation and characterisation of human cortical interneurons reporter stem cell lines

Cortical interneurons are GABAergic inhibitory neurons localised in the cerebral cortex where they establish local connections and regulate the excitatory/inhibitory input onto cortical networks. Cortical interneuron dysfunction is thought to underlie the aetiology of neurodevelopmental disorders (NDDs), such as autism, schizophrenia and epilepsy. The ability of human pluripotent stem cells (hPSCs) to give rise to any cell type of the body make them a valuable tool to study cell fate specification. Moreover, they can provide an unlimited source of interneuron populations for diseases modelling, drug screening and regenerative medicine purposes. Nonetheless, such application can be greatly benefited by the generation of reporter cell lines that allow the identification of specific cell types, which in turn can facilitate the development of better differentiation protocols. This thesis reports the generation of a LHX6-mCherry/PV-GFP reporter cell line for tracking hPSC-derived cortical interneurons. The reporter cells can readily acquire medial ganglionic eminence (MGE)-like identity upon in vitro differentiation, with mCherry signal restricted to the MGE lineage and faithfully labels LHX6+ cells. These findings validate the potential of this reporter line as a useful tool for future investigations into potential MGE-fate determinants and interneuron subtype specification. However, the poor efficiency in generating parvalbumin+ neurons limited the functional verification of the PV-GFP reporter. I then exploited the LHX6-mCherry reporter cells in an investigation of TGFβ signalling in cortical interneuron development. Pharmacological inhibition of this pathway keeps the MGE-like cells as progenitors through prolonging the cell cycle, while the addition of exogenous TGFβ3 accelerated mCherry+ cells production (postmitotic-cells). These findings unravelled a novel function of TGFβ signalling in controlling the balance between MGE-like progenitor maintenance and neuronal differentiation