Confocal microscopic studies revealed that immunoreactivity for CD31 per unit volume in the border area within the ischemic core in the OGD-microglial transplantation group was more prominent than that in the no cell control group and OGD-preconditioned astrocytic transplantation group at 28 days after cerebral ischemia (at 21 days after transplantation) (P < 0.001 and P < 0.001). Here, PECAM1 is linked to brain ischemia.