Dissociative increase of oligodendrocyte progenitor cells between young and aged rats after transient cerebral ischemia.

Oligodendrocyte progenitor cells (OPCs) mature to oligodendrocyte and remyelinate axons. OPCs express neuron-glial antigen 2 (NG2) chondroitin sulfate proteoglycan. We stained NG2 to investigate the effect of aging on the OPCs after cerebral ischemia. NG2 positive cells were examined at 1, 3, 7 days after 90 min of transient middle cerebral artery occlusion in young and aged brains. The number of NG2 positive cells increased in the ischemic penumbra at 3 and 7 days after reperfusion. At 7 day, the number of NG2 positive cells was significantly greater in the young than the aged brains, and the processes of NG2 positive cells enlarged and were more highly branched in the young than the aged brains. These results suggest that the young brain shows a higher potential of proliferation and process branching of OPCs than the aged brain.