Fig. 8

Microglial depletion results in an increased loss of neurons and oligodendrocytes leading to greater tissue damage after SCI. (a and b, d and e, g and h, j and k) Confocal immunofluorescence of astrocytes (GFAP⁺, blue), microglia (TdT⁺, red cells in a–b, d and e), blood-derived myeloid cells (LysM-eGFP⁺ or CD11b⁺, green cells in a and b, d and e, k), neurons/axons (NF-H⁺, green in g and h, j) and pericytes/fibroblasts (PDGFRβ⁺, red cells in g and h, j) at the lesion epicenter at 7 (a and b), 14 (d and e) and 35 (g and h) dpi. Yellow and purple lines, respectively, delineate the contours of the primary (core) and satellite lesions, which were surrounded by astrocytic endfeet and characterized by the absence of neuronal elements and presence of cells of non-CNS origin (blood-derived myeloid cells, pericytes, and fibroblasts). Satellite lesions are shown in a microglia-depleted mouse at 35 dpi (j and k). c Quantification of the total lesion area at 7 dpi in mice fed the control diet (blue), PLX73086 (red), or PLX5622 (green) (n = 5–6 mice/group). f, i Quantification of the total area occupied by satellite lesions at 14 (f) and 35 (i) dpi (n = 5–7/group). l and m Quantification of the number of neurons (HuC/HuD⁺) in the uninjured spinal cord (l), as well as rostral (R) and caudal (C) to the epicenter (m), in mice treated with PLX5622, PLX73086, or control at 35 dpi (n = 5–8/group). n and o Representative confocal images taken at the lesion epicenter at 35 dpi immunostained for HuC/HuD (red). DAPI is shown in blue. p, q Quantification of the number of oligodendrocytes (Olig2⁺ CC1⁺) in the uninjured (p) and injured (q) spinal cord of mice treated with PLX5622, PLX73086 or control at 35 dpi (n = 5–8/group). Data are expressed as mean ± SEM. *p < 0.05, **p < 0.01, ***p < 0.001, ****p < 0.0001, PLX5622 versus control; ^#p < 0.05, PLX73086 versus control; and ^&p < 0.05, ^&&p < 0.01, ^&&&p < 0.001, ^&&&&p < 0.0001, PLX5622 compared to PLX73086. Statistical analysis was performed using a two-way ANOVA followed by a Bonferroni’s post hoc test. Scale bars: (a and b, d and e, g and h in h) 200 µm, (j and k) 50 µm, (n and o, in o) 50 µm