The influx of monocytes into the injured brain after mTBI.

<p>In these experiments, the depth of brain deformation was set at 1 mm, and the images shown were acquired at 24 h post-mTBI. Double immunostaining of injured brains was performed with anti-CD68 antibody, a monocyte marker, and an antibody to von Willebrand factor (vWF), a marker for endothelial cells. (A, B) Similar to severe TBI, in mTBI, monocytes did not appear in the injured brain until 24 h after the impact. However, only a small number of monocytes invaded the injured brain parenchyma at 24 h post-mTBI. Note that at this time point after injury, these inflammatory cells were predominantly located close to intraparenchymal blood microvessels. (C, D) In contrast to brain parenchyma, a large number of monocytes crossed the pial microvessels and invaded the subarachnoid space (SAS) near the injury site. Note that some of these monocytes appeared to subsequently move along the perivascular space to enter the brain parenchyma (arrows). (E–G) An influx of monocytes into the ipsilateral cistern of velum interpositum (CVI) also occurred at 24 h post-mTBI. Bars: panels A, B, E, 100 μm; panels C, D, F, G, 50 μm.