Generation of human cerebral organoids with a structured outer subventricular zone

Outer radial glia (oRG) emerged during mammalian evolution as cortical progenitor cells that directly support the development of an enlarged outer subventricular zone (oSVZ) and, in turn, the expansion of the neocortex. The in vitro generation of oRG is essential to model and investigate the underlying mechanisms of human neocortex development and expansion. By activating the STAT3 pathway using LIF, which is not produced in guided cortical organoids, we developed a cerebral organoid differentiation method from human pluripotent stem cells (hPSCs) that recapitulates the expansion of a progenitor pool into the oSVZ. The structured oSVZ is composed of progenitor cells expressing specific oRG markers such as GFAP, LIFR, HOPX and closely matching human oRG in vivo. In this microenvironment, cortical neurons showed faster maturation with enhanced metabolic and functional activity. Incorporation of hPSC-derived brain vascular LIF-producing pericytes in cerebral organoids mimicked the effects of LIF treatment. These data indicate that the cellular complexity of the cortical microenvironment, including cell types of the brain vasculature, favors the appearance of oRG and provides a platform to routinely study oRG in hPSC-derived brain organoids.