Oligogenesis and Oligodendrocyte Progenitor Maturation Vary in Different Brain Regions and Partially Correlate with Local Angiogenesis after Ischemic Stroke

Oligogenesis plays an important role in functional recovery after ischemic stroke. We tested the hypothesis that oligogenesis and the maturation of oligodendrocyte progenitor cells (OPCs) vary in different brain regions using a rat transient middle cerebral artery occlusion (tMCAO) model. Compared to day 1, olig2(+) OPCs and oligodendrocytes (OLGs) increased in the peri-infarct basal ganglia (BG) 7 days (44%) and 14 days (61%) after 2 h of MCAO; OPCs (PDGFR alpha(+)) and OLGs (CC1(+)) increased in this region 14 days after tMCAO by 139% and 126%, respectively. Although the olig2(+) cells and OLGs did not increase significantly in the peri-infarct cortex (CTX), the OPCs increased in this region by 95% at day 14 vs. day 1 after tMCAO. The numbers of OPCs and OLGs remained low after an initial reduction at day 1 in the peri-infarct corpus callosum (CC). Correlation analyses showed that the numbers of olig2(+) cells (r=0.73, P=0.03) and OLGs (r=0.74, P=0.02) correlated with local vessel density; however, the number of OPCs did not correlate with vessel density (r=0.43, P=0.24). Our data show that oligogenesis and the maturation of OPCs differ in various brain regions and the difference in regional angiogenic response is one of the potential reasons.