Gene expression profile at single cell level of human cerebral cortical organoids with and without LIF treatment
Proper regulation of the proliferation and differentiation of radial glia (RG), the neural stem cells of the developing cortex, is fundamental for brain growth and organization. In humans, a specialized RG subtype, the outer radial glia (oRG), are abundant and give rise to diverse neuronal and glial progeny. However, the mechanisms regulating oRG development and differentiation are not fully understood. Here we investigated the regulation of oRG expansion and lineage potential by perturbing Leukemia Inhibitory Factor (LIF) signaling in the developing human cortex and in human pluripotent stem cell (PSC)-derived cortical organoids. LIF receptors are specifically expressed in oRG cells during neurogenesis, and, consistent with the previously described role of this cytokine as an activator of stem cell self-renewal, LIF treatment increased the number of oRG cells. Surprisingly, LIF treatment also increased the production of inhibitory interneurons (INs) in the cortex. Comparative transcriptomic analysis suggested that these INs resemble INs produced in the caudal ganglionic eminence (CGE). To test if oRG cells are the progenitors of these CGE-like INs, we isolated oRG cells from primary developing cortex and cultured them for several weeks with and without LIF treatment. We found that CGE-like INs were produced by oRG cells, and their abundance is increased by LIF treatment. Together, these observations suggest that LIF signaling regulates oRG lineage potential and capacity to generate CGE-like INs. Overall design: We cultured cerebral cortical organoisds with and without LIF treatment for up to 15 weeks. For short-term treatment, LIF was added between weeks 6-8 in the treatment group, and organoids were harvested at weeks 8, 10, and 15 for single-cell RNA sequencing. For long-term treatment, LIF was added between weeks 5-15 in the treatment group, and organoids were harvested at weeks 8, 10, and 15 for single-cell RNA sequencing.