Comparison of the microenvironment of the injured spinal cord at 9 DPI versus 42 DPI. A, Representative images of HE staining and immunofluorescence staining for GFAP, CS56, and Iba1 in sagittal sections. B, CSPGs accumulation was more prominent at the lesion site at 42 DPI than at 9 DPI. Values are means ± SEM (n = 3). *P < 0.05. C, More Iba1-positive cells were distributed at the lesion site at 9 DPI than at 42 DPI. Values are means ± SEM (n = 3). *P < 0.05. D, Overview of all the microarray data by PCA. The samples of each group were clustered at different locations on 3D visualization. E, Hierarchical clustering analysis showed that the gene expression pattern at 9 DPI was similar to that at 42 DPI. However, the magnitude of changes in gene expression differed between the two injury groups. Green tiles show downregulated genes and red tiles indicate upregulated genes. F-H, Gene expression signals of cytokines (F), growth factors (G), and markers of inflammatory cells (H) at 9 DPI and 42 DPI. The gene expression levels of markers associated with microglia/macrophages significantly differed between 9 DPI and 42 DPI, but those of all cytokines and growth factors did not. Data are the mean fold-change values versus intact samples. Values are means ± SEM (n = 3). *P < 0.05, **P < 0.01, ***P < 0.001. I, Representative images of immunofluorescence staining for Iba1, arginase-1, and LAMP2 in sagittal sections of the lesion epicenter at 9 DPI and 42 DPI. Arrows: Iba1+/arginase-1+/LAMP2+ triple-positive cells. J, At the lesion epicenter, more Iba1+/arginase-1+ M2 macrophages had infiltrated at 9 DPI compared with 42 DPI. Values are means ± SEM (n = 3). **P < 0.01. Scale bar: 1000 μm in (A) and 50 μm in (J).