iVPCs engrafted into blood vessels after implantation into rat ischemic myocardium. Images are from immunostaining of rat myocardium in control group and iVPC- and iPSC-implanted group after 10 days of the RI protocol. DAPI staining reveals cell nuclei. (A) Immunostaining of rat myocardium with ES cell marker SSEA-1 (green) and endothelial cell marker VWF (red). In control group, there was no obvious SSEA-1 expression. The iVPC- and iPSC-implanted groups highly expressed SSEA-1 and co-localized with vascular ECs. In the bottom panel, iVPCs branched and split from one big vessel into several small vessels, which is one type of angiogenesis (intussusceptive angiogenesis). (B) Immunostaining of rat myocardium with ES cell marker SSEA-1 (green) and vascular smooth cell marker αSMA (red). In the control group, again there was no obvious SSEA-1 expression. In the iVPC-implanted group, iVPCs expressing SSEA-1 co-localized with VSMCs. However, no co-localization of iPSCs with VSMCs was observed. (C) Immunostaining of rat myocardium with cardiomyocytes marker α-sarcomeric actin. In the iVPC delievered group, there was no co-localization of iVPCs with cardiomyocytes, but in the iPSC-implanted group, co-localization of iPSCs with cardiomyocytes was observed. Scale bar equals 100μm in A and B and 10μm in C.