Decoding the spatiotemporal development of human meninges.

The human meninges are essential regulators of central nervous system (CNS) development and homeostasis. However, a comprehensive spatiotemporal characterization of the cellular and molecular dynamics during human meninges development is currently lacking. Using single-cell spatiotemporal transcriptomics across 6-23 gestational weeks (GWs), we identify asynchronous meningeal layer development, with the pia mater forming earliest. We define layer-specific fibroblast states from the three meningeal layers, including the expression of barrier-related genes, neurotransmitter transporter-related and synapse-related genes, and lipid metabolism-related genes. We further characterize spatiotemporal heterogeneity in meningeal immune cells, identifying a meningeal-specific macrophage population. The pia mater recruits and spatially organizes immune cells, particularly macrophages in the leptomeninges via CXCL12-CXCR4 signaling. Moreover, Trem2+ macrophages, in turn, regulate the development of Cajal-Retzius (CR) cells in the cerebral cortex. These findings establish a spatiotemporal framework for human meningeal development, uncover neuro-immune interactions that shape cortical development, and identify potential therapeutic targets.