Transplanted Adult Neural Stem Cells Express Sonic Hedgehog In Vivo and Suppress White Matter Neuroinflammation after Experimental Traumatic Brain Injury

Figure 2

Induced genetic in vivo labeling to detect Shh expression following traumatic brain injury (TBI). (a) Shh^CreERT2;R26tdTomato mice received tamoxifen (TMX) 2 and 3 days after TBI or sham surgery and were perfused at 2 weeks postsurgery. (b) Diagram showing impact to the skull at bregma corresponded with the coronal level of the anterior commissure (ac). (c–g) Coronal sections with Shh transcription evident via the tdTomato reporter (Shh-Tom, red). GFAP immunolabeling (green) to detect astrocytic response to TBI. DAPI nuclear stain (blue) to identify cortical layers (I–VI). (c) Shh-Tom cells with neuronal morphology in the striatum near the SVZ and lateral ventricle (LV). Similar Shh-Tom cells in the striatum are colabeled with the neuronal marker NeuN (Figure S). (d–e) Shh-Tom labeling in distributed cortical cells identified as neurons by morphology (d) and (e) colabeling with NeuN (Figure S). GFAP immunolabeling in the cortex showed mild cortical astrogliosis after TBI (d–e). Shh-Tom cells did not have an astrocytic morphology or colabel for GFAP (d–e). (f–g) Shh-Tom labeling of axons in the cingulum (cg) and corpus callosum (cc) was similar in sham (f) and TBI (g) mice. After TBI, reactive astrocytes in the corpus callosum were not colabeled with Shh-Tom (g). (h–i) Shh-Tom axons were found in the corpus callosum but at a very low density. Normal variation of Shh-Tom labeling along the length of axons in a sham mouse (arrow; (h)). Consistent with axon damage after TBI, rare pathological swellings were observed in Shh-Tom-labeled axons (arrow; (i)). Scale bars = 1 mm (b), 100 μm (c, d, f), 50 μm (h). Representative images are shown from analysis of a cohort of sham () and TBI () mice.