Spatial and temporal heterogeneity of mouse and human microglia at single-cell resolution

Microglia play critical roles in neural development and homeostasis. They are also implicated in neurodegenerative and neuroinflammatory diseases of the central nervous system (CNS). However, little is known about the presence of spatially and temporally restricted subclasses of microglia during CNS development and disease. Here, we combined massively parallel single-cell analysis, single-molecule FISH, advanced immunohistochemistry and computational modelling to comprehensively characterize novel microglia subclasses, which were transcriptionally different from perivascular macrophages, in up to six different CNS regions during development and diseases. Single-cell analysis revealed specific time- and region-dependent microglia subtypes during homeostasis. In contrast, demyelinating and neurodegenerative diseases evoked context-dependent microglia subtypes with distinct molecular hallmarks and diverse cellular kinetics. Finally, diverse microglia subsets were also identified in normal and diseased human brains. Our data provide new insights into the CNS endogenous immune system during development, health and perturbations. CD45+ cells isolated from healthy and MS-affected human brains were FACS-sorted in 384-well plates and used for scRNAseq. The patients were aged between 22 and 25 years. Data comprises 5 healthy and 5 MS patients. CEL-Seq2 protocol was used for single cell sequencing (Hashimshony et al. 2016).