Neurogenesis after primary intracerebral hemorrhage in adult human brain

Abstract

Neurogenesis occurs in discrete regions of normal brains of adult mammals including humans, and is induced in response to brain injury and neurodegenerative disease. Whether intracerebral hemorrhage can also induce neurogenesis in human brain is unknown. Specimens were obtained from patients with primary intracerebral hemorrhage undergoing surgical evacuation of an intracerebral hematoma, and evaluated by two-photon laser scanning confocal microscopy. We found that neural stem/progenitor cell-specific protein markers were expressed in cells located in the perihematomal regions of the basal ganglia and parietal lobe of the adult human brain after primary intracerebral hemorrhage (n=5). Cells in this region also expressed cell proliferation markers, which colocalized to the same cells that expressed neural stem/progenitor cell-specific proteins. Our data suggest that intracerebral hemorrhage induces neurogenesis in the adult human brain.

Figure 1

Expression of NSC marker proteins in the perihematomal region after ICH in adult human brain. (A) TUJ-1 shown at low (left) and high (right) magnification. (B) Nestin shown at low (left) and high (right) magnification, both adjacent to (top right) and at a distance from (bottom right) the hematoma. (C) DCX at low and high (inset) magnification. (D) Musashi1. (E) TUC-4. (F) The number of NSC-positive cells and proliferative cells in the perihematomal region after ICH.

Figure 2

Coexpression of NSC and related markers in the perihematomal region after ICH. (A) Cells positive for DCX (green) and Musashi1 (red), including a cell that expresses both markers (arrow), shown at high magnification in the inset. (B) Cell expressing DCX (green) and TUJ-1 (red). (C) Cells expressing DCX (green) and TUC-4 (red). (D) Cells expressing GFAP (purple), CD11b (red), and DCX (green). Yellow arrow: CD11b-positive cell expresses GFAP; green arrows: CD11b-positive cells do not express GFAP. Nuclei are counterstained with DAPI (blue).

Figure 3

Presence of proliferative cells in perihematomal region after ICH. (A) Ki67-positive cells (red) are shown in relation to all cells (DAPI-stained nuclei, blue) at low (left) and high (right) magnification. (B) Ki67 (red) is colocalized with minichromosome maintenance 2 (green) in the nucleus (DAPI staining, blue) of cells adjacent to the hematoma. (C) Ki67 (green) is colocalized with proliferating cell nuclear antigen (red) in the nucleus of a perihematomal cell (seen at far right in low-magnification panels).

Figure 4

Relationship between Ki67 reactivity and caspase-3 activation. Ki67 (red) is expressed in the perihematomal region after ICH. Ki67 colocalizes with a cell death marker, the 17 to 20 kDa cleavage product of caspase-3 (green), in some (misshapen nuclei, white arrows) but not all (normal nuclei, green arrows) cells. Nuclei are counterstained with DAPI (blue).

Figure 5

Coexpression of neuronal lineage and cell proliferation markers in perihematomal regions after ICH. (A) A section stained for TUJ-1 (red cytoplasm) and Ki67 (green nucleus) shows that TUJ-1-positive cells express Ki67. (B) A TUC-4-positive (red cytoplasm) cell also expresses Ki67 (green nucleus). (C) DCX (green cytoplasm) is colocalized with the cell proliferative marker Ki67 (red nucleus). (D) GFAP-positive (red cytoplasm) cells do not colocalize with Ki67 (green nucleus). (E) CD11b-positive (red cytoplasm) cell expresses GFAP (purple) but not Ki67 (green). Nuclei in all panels are counterstained with DAPI (blue).