Abstract 52: Changes in Oligodendrocyte Sub-Populations After Neonatal Stroke

Abstract

Background: Chronic white matter changes after neonatal stroke have not been well studied. Histologically, we see a robust increase in oligodendrocytes (OLs) in injured striatum 14 days post-middle cerebral artery occlusion (MCAO) in neonatal mice. The contribution of these cells to chronic white matter injury and repair has not been evaluated. Objective: Evaluate changes in striatal OL cell gene expression after neonatal MCAO. Methods: Mice underwent 60 minutes of MCAO at postnatal day 10 using the filament model and sacrificed 14 days later for fluorescent antibody cell sorting and single cell RNA sequencing. Single cell suspensions from Injured (ipsilateral) and uninjured (contralateral) striata were incubated with antibodies to immature and mature OLs. Cells expressing OL markers were collected and captured using 10x Genomics Chromium with V3.1 chemistry and analyzed in Seurat V3.1. Results: We captured a total of 4598 cells, with ~250,000 reads per cell. Our data set was comprised of 2399 oligodendrocytes (915 Contralateral, 1484 Ipsilateral). Feature plots of OL markers demonstrate that the entire lineage is present in our cell population (Fig 1A). Unbiased clustering identified 10 sub-populations of oligodendrocytes (Fig 1B). In ipsilateral striatum there was a significant decrease in the proportion of cells in cluster 8 (p <0.0001, proportions test, Fig 1C), which also express OL progenitor cell (OPC) markers. There was a significant increase in the proportion of cells in clusters 1 and 5. Pathway analysis suggest that both these clusters are comprised of pre-myelinating oligodendrocytes. Conclusions: At 14 days after neonatal stroke in mice scSEQ reveals a depletion of an OPC sub-population and an increase in sub-mature clusters of oligodendrocytes in ipsilateral striatum. Ongoing analysis of differential gene expression will reveal new insights into these cells and potential targets to promote white matter repair after neonatal stroke.