Epicardial Hypoxia Stimulates Epicardial cxcl12b Expression and Coronary EC Proliferation via Hif1a (A) qPCR analysis of aldh1a2 and egln3 mRNA levels in sorted tcf21:RFP+ cells from 7 dps and 7 dpci ventricles (n = 4). (B and C) 7 dps (B) and 7 dpci (C) ventricles stained for epicardium (green), hypoxyprobe (red), and DNA (blue). Insets show high-magnification images of sham (B) and regenerating (C) epicardium. (D) qPCR analysis of cxcl12b mRNA levels in WT ventricles at 7 dps (n = 4) and 7 dpci (n = 4) and in hif1a−/− ventricles at 7 dpci (n = 4). (E and F) WT (E) and hif1a−/− (F) ventricles stained for endothelial nuclei (red), PCNA (green), and DNA (blue). Insets show high-magnification images of proliferating cECs (white arrowheads). (G–I) cEC proliferation in WT (n = 4), and hif1a−/− (n = 4) ventricles at 96 hpci (G). Ventricles from PBS- (H) and DMOG- (I) treated animals stained for endothelial nuclei (red), PCNA (green), and DNA (blue). Insets show high-magnification images of proliferating cECs (white arrowheads). (J) cEC proliferation in PBS- (n = 4), and DMOG- (n = 4) treated ventricles at 96 hpci. White dotted lines delineate the injured area. Data in graphs expressed as mean ± SEM. ns, no significant difference, ∗p < 0.05, ∗∗p < 0.01. Scale bars: 100 μm.
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