Adult Leptomeninges are Regionally Patterned and Provide Specialized Support to Underlying Brain Tissue

The leptomeninges envelop the central nervous system and contribute to brain homeostasis by producing trophic factors and regulating entrance of cells, factors and agents, immune responses and cerebrospinal fluid production. We report that leptomeninges from adult mice are regionally patterned. Leptomeninges dissected from anterior or posterior aspects of the forebrain grown in hetero- or homo-typic culture with anterior and posterior cortical cells demonstrate differences in ability to support survival of neuronal subsets and proliferation of progenitors for astrocytes and oligodendrocytes. Meningeal support changes with age: co-culture with 18-month old leptomeninges reduced numbers of cortical progenitor cells and neurons but increased astrocyte expansion. Analysis of cytokine secretion and single cell RNA-sequencing revealed differences in anterior versus posterior, young versus old meningeal factors and composition. These data demonstrate that adult leptomeninges are regionally patterned in cell composition and functional properties, and suggest that meningeal deficits may contribute to brain aging and disease. Overall design: A pool of six male C57B6 mice per timepoint (3 or 18 months old) were used to obtain anterior and posterior meningeal cells.