Mapping the cellular and molecular organization of mouse cerebral aging by single-cell transcriptome imaging

The enormous cellular diversity and complex tissue organization of the brain have hindered systematic characterization of its age-related changes in cellular and molecular architecture and mechanistic understanding of its functional decline and degeneration during aging. Here we generated a high-resolution cell atlas of brain aging within the frontal cortex and striatum using spatially resolved single-cell transcriptomics and quantified the changes in gene expression and spatial organization of major cell types in these regions over the lifespan of mice. We observed more pronounced changes in the composition, gene expression and spatial organization of non-neuronal cells over neurons. Our data revealed molecular and spatial signatures of glial and immune cell activation during aging, particularly within the white matter of the corpus callosum, and identified both similarities and differences in cell activation patterns induced by aging and systemic inflammatory challenge. These results provide critical insights into age-related decline and inflammation in the brain. Nuclei of 2 young (4 week old) and 2 aged (90 week old) mice were isolated by fluorescence-activated cell sorting (FACS) according to the presence of Hoeschst signal and analyzed using 10X Genomics snRNA-seq.大脑拥有极其丰富的细胞多样性与复杂的组织结构，这极大阻碍了学界对其衰老过程中细胞与分子层面结构的年龄相关变化开展系统性表征，也妨碍了对其衰老期间功能衰退与退行性病变的机制性理解。本研究利用空间分辨单细胞转录组学（spatially resolved single-cell transcriptomics）技术，构建了小鼠前额叶皮层（frontal cortex）与纹状体（striatum）脑区衰老的高分辨率细胞图谱，并量化了小鼠整个生命周期中这两个脑区内主要细胞类型的基因表达与空间组织变化。我们观察到，非神经元细胞的组成、基因表达及空间组织的变化程度显著高于神经元细胞。本研究数据揭示了衰老过程中胶质细胞与免疫细胞激活的分子与空间特征，尤其在胼胝体（corpus callosum）白质区域，并明确了衰老与系统性炎症刺激所诱导的细胞激活模式的异同之处。上述研究结果为理解大脑的年龄相关性衰退与炎症反应提供了关键见解。本研究通过荧光激活细胞分选（fluorescence-activated cell sorting, FACS），基于Hoechst信号筛选分离了2只年轻（4周龄）与2只老年（90周龄）小鼠的细胞核，并利用10X Genomics单细胞核RNA测序（single nuclear RNA sequencing, snRNA-seq）进行了分析。