Fig. 1

Features of the CD163⁺ macrophages in the acute phase of stroke. a) CD163 immunohistochemistry in paraffin brain sections 8 h after MCAo shows CD163⁺ cells (brown) in perivascular and subpial spaces of the contralateral and ipsilateral hemispheres. Panels in the right are magnifications of the squares in the adjacent panels. Images are representative of four rats. Scale bar = 10 μm. b) Flow cytometry of myeloid cells in the control (n = 2) and ischemic brain tissue 16 h (n = 4) and 24 h (n = 7) after MCAo. The population of CD163⁺ cells (orange) is maintained after ischemia, but the population of CD45^hiCD11b⁺ cells (blue) progressively increases due to infiltration of peripheral myeloid cells to the ischemic tissue. Microglial cells (CD45^lowCD11b⁺) are shown in red. c) Quantification of the brain myeloid cell populations within all live cells by flow cytometry. For each animal, we calculated the fold increase in the ischemic (ipsilateral, ipsi) hemisphere versus the contralateral (contra) hemisphere. As expected, the ratio between the right/left hemispheres in control rats was equal to 1 (mean±SD, 0.965 ± 0.05 for CD45^hiCD11b⁺ cells, and 1.115 ± 0.05 for CD163⁺ cells). The ratio ipsi/contra progressively increased after ischemia for CD45^hiCD11b⁺ CD163⁻ cells (*p < 0.05, Kuskall-Wallis test followed by post-hoc Dunn’s test). In contrast, the ratio ipsi/contra for CD163⁺ cells was similar to controls at 16 h and the increases at 24 h were very small and not statistically significant. Values in the graph are expressed as the mean and SD of the indicated number of rats per group