Supplementary Fig. 4: Temporary Microglial Activation at Chase Injection Sites.

Images of transverse sections immediately adjacent to injection sites (or similar regions in C8-T1 spinal cord for uninjected subjects), labeled for IBA1 (microglia) at the indicated time points. There are significant differences in density of IBA1 labeling across groups (Overall ANOVA: F_{(5, 197.30)} = 4.43, P = 0.009). Analyses include sections from animals involved in a previous study (;³⁰ N=3 Intact subjects, N=4 Lesion 2wk subjects, N=3 Lesion 5mo subjects). Main panels show example actual images used for quantification; insets are 3x zooms. Images shown are from subjects whose results were closest to their group’s mean value. Quantifications in panel G. (A) Intact subjects show the baseline level of microglial labeling. (B) Two weeks after lesion, a trend toward increased microglial labeling is observed compared to baseline (N=4 subjects, ANOVA: F_{(1, 144.57)} = 2.79, P = 0.16, compared to N=3 Intact subjects). (C) Two weeks after Chase injections (six weeks after lesion), increased IBA1 labeling is evident immediately adjacent to the injection site (arrow) (N=2 subjects). (D-F) At longer time points after lesions, increased IBA1 labeling remains evident and statistically significant compared to intact baseline (Lesion 5mo, N=5 subjects, ANOVA: F_{(1, 435.10)} = 6.74, P = 0.04; Saline 4mo, N=3 subjects, ANOVA: F_{(1, 277.44)} = 10.34, P = 0.03; Chase 4mo, N=6 subjects, ANOVA: F_{(1, 479.47)} = 35.19, P = 0.0006; all compared to N=3 Intact subjects). However, there are no significant differences among animals with lesions alone, Saline injections or Chase injections (Lesion 5mo vs. Saline 4mo, vs. Chase 4mo, ANOVA: F_{(2, 3.78)} = 0.11, P=0.89). (G) Bar graphs show means, data points are individual subjects, error bars represent SEM, asterisks indicate statistical difference from intact baseline, statistical results described above. Scale bar: 200 μm.