Project Summary/Abstract Glia (astrocytes, microglia, and oligodendrocytes) and vascular cells are critical for the development and function of the central nervous system. Glial and vascular defects are associated with aging and neurodegeneration. Juvenile brains exhibit remarkable plasticity and resilience that diminish when brains mature. The potential contribution of glia and vascular cells to the plasticity of juvenile brains and the diminution of regenerative potentials in adult and aging brains remain poorly understood. Investigating molecular differences between juvenile and mature glia and vascular cells holds promise for the identification of protective factors in the brain. We recently developed immunopanning methods to purify astrocytes, microglia, oligodendrocytes, neurons, and vascular cells from both human and mouse brains. Cell populations isolated by immunopanning have high purity and produce abundant RNA for transcriptome profiling by RNA-sequencing (RNA-seq). Sequencing of purified populations of cells provides higher sensitivity for the detection of differential gene expression than alternative methods such as single cell RNA-seq. Using immunopanning, we purified astrocytes from a series of developmental stages from both human and mouse brains. In this proposed study, we will first perform bioinformatics analysis of our juvenile and mature astrocyte datasets and identify differentially expressed genes at each stage (Aim 1). Human and mouse evolution separated about 100 million years ago. Translating discoveries made in mouse models into clinics has been challenging. Our human and mouse astrocyte datasets will allow us to identify developmentally regulated molecular pathways preserved through a hundred million years of evolution and therefore likely to be essential. These analyses will generate candidate astrocytic juvenile protective factors that can be tested in future studies. Furthermore, we will expand our RNA-seq comparison of juvenile and mature cells to neurons, microglia, oligodendrocytes, and endothelial cells using immunopanning purified cell populations (Aim 2). These systematic analyses have the potential to reveal candidate juvenile protective factors in each cell type, improve our understanding of the roles played by each cell type in brain maturation and aging, and uncover candidate molecular pathways to target in the treatment of aging and neurodegeneration. The proposed study will build the foundation for a larger scale study that tests the function of candidate juvenile protective factors in neurons, glia, and vascular cells.