Glucose and Oxygen Metabolism Coordinate Human Cortical Developmental Decisions
Defining metabolic regulation of neurodevelopmental programs is essential to approach developmental disorders and injuries driven by alterations in metabolism. In vitro cultures are the only available method to temporally perturb and study living human brain cells throughout neurogenesis, however most culture systems use supraphysiologic conditions of essential nutrients, glucose and oxygen. We probed how environmental exposure to endogenous-like concentrations impact metabolic state and developmental progression of cortical cell types using organoids. Nutrient accessibility globally impacted metabolic state, yet developmental responses to metabolic changes were cell type-specific. Metabolomic and transcriptomic datasets reveal increased TCA metabolites and amino acids and oxidative phosphorylation (OXPHOS) genes, under physiologic glucose conditions. Oxygen level had a modest, yet specific, molecular impact on deep layer excitatory neurons. We assessed consequences of metabolic changes on fate and observed that physiologic glucose expanded the human-enriched population of cortical stem cells, outer radial glia, and their progeny, upper layer excitatory neurons. Alterations in oxygen, instead, affected production of neurogenic progenitors and neuronal differentiation, with higher oxygen availability supporting shifts toward mitochondrial metabolism necessary for maturing cell types. We functionally tested this transition by inhibiting glycolysis; total inhibition promoted neuronal differentiation, whereas inhibition of anaerobic glycolysis/lactate production led to oRG expansion. Lactate signaling was sufficient to suppress oRG development and promote self-renewal of neurogenic progenitors. These data suggest that refined metabolic switches and decreased reliance on glucose are required for transition from stem cell self-renewal to more mature, diversified progenitor subtypes, where switch from anaerobic to aerobic metabolism discretely impacts progenitor diversification.