PECAM1 and Stroke: With immunostaining of BrdU+/CD31+ new formed vessels, the expression of BrdU+/CD31+ cells in the COs transplantation group was more than that in MCAO group at 7 and 28 dpi (116.14 ± 6.92 vs. 49.00 ± 6.27 at 7 dpi, 160.71 ± 29.39 vs. 46.86 ± 4.44 at 28 dpi, Fig. 7b, c), indicating that COs transplantation did promote angiogenesis after stroke.