Figure 3.

Partial depletion of microglia/macrophages at the late stage after MCAo promotes a GFP⁺ OPC response but has no impact on their maturation

(A) Schematic representation of the experimental protocol exploited for late depletion of microglia/macrophages after MCAo. (B) Representative images of cells stained for Iba1, CD16/32, Ym1, and GFP at the boundary of the ischemic lesion (0−500 μm) at day 17 post-MCAo following intranasal administration of GdCl₃ or vehicle. Scale bars, 50 μm. (C) Quantification of the density of total Iba1⁺, Iba1⁺ and CD16/32⁺, and Iba1⁺ and Ym1⁺ cells at the boundary of the ischemic lesion (0−500 μm) at day 17 post-MCAo following intranasal administration of GdCl₃ or vehicle (n = 5). Data are expressed as mean ± SE. Student’s t test. (D) Quantification of the density of GFP⁺ OPCs at the boundary of the ischemic lesion (0−500 μm) at day 17 post-MCAo following intranasal administration of GdCl₃ or vehicle (n = 6). Data are expressed as mean ± SE. Student’s t test. (E) Scatterplot representation of the linear correlation between the densities of Iba1⁺ cells (x axis) and GFP⁺ OPCs (y axis) at the boundary of the ischemic lesion (0−500 μm) at day 17 post-MCAo. Green dots correspond to GdCl₃-treated animals, whereas blue dots represent vehicle-treated animals. For correlation analysis, two-tailed Pearson test was used. (F) Representative images of cells stained for GFP and GSTπ at the boundary of the ischemic lesion (0−500 μm) at day 42 post-MCAo following intranasal administration of GdCl₃ or vehicle. Scale bars, 50 μm. Magnifications show cells co-expressing GFP and GSTπ: scale bars, 25 μm. (G) Quantification of the density of total GFP⁺ OPCs and GFP⁺ and GSTπ⁺ cells at the boundary of the ischemic lesion (0−500 μm) at day 42 post-MCAo following intranasal administration of GdCl₃ or vehicle (n = 5−6). Data are expressed as mean ± SE. Student’s t test. (H) Representative images of myelin visualized using FluoroMyelin Red stain in the corpus callosum (delimited by white dashed lines) at the boundary of the ischemic lesion (0−500 μm) at day 42 post-MCAo, following intranasal administration of GdCl₃ or vehicle. Scale bars, 50 μm. (I) Quantification of the percentage of FluoroMyelin⁺ area in the corpus callosum at the boundary of the ischemic lesion (0−500 μm) at day 42 post-MCAo, following intranasal administration of GdCl₃ or vehicle (n = 5−6). Data are expressed as mean ± SE and normalized to vehicle set to 100.