Adult WT, Angpt1^iΔ/Δ (A1ΔU), or Angpt2^iΔEC (A2ΔE) mice were subjected to MI or sham procedure, and hearts were harvested at 3 days after MI. (A and B) Images and comparisons of Angpt1 expression in heart of Angpt1-GFP mice at 3 days after sham or MI procedure. Each region marked by a box demonstrating the expression of Angpt1 in myocardium is magnified in the right corner. Scale bars: 500 μm. n = 4–5. (C) Diagram depicting generation of Angpt1^iΔ/Δ or Angpt2^iΔEC mice and experiment schedule. (D and E) Immunofluorescence images and quantification show the decrease in pTie2 in border zone ECs after MI; pTie2 level was lower in Angpt1^iΔ/Δ mice, but higher in Angpt2^iΔEC mice compared with WT. Scale bars: 100 μm. n = 5–6, each time point. *P < 0.01, Kruskal-Wallis test followed by Mann-Whitney U test for post hoc pairwise comparisons. (F and G) Images and comparisons of NG2⁺ pericyte (PC) coverage on ECs at the border zone. Direction of arrow indicates the border zone closer to infarct area. Dashed lines distinguish PC^hi/Angpt2^lo region from PC^lo/Angpt2^hi region at the infarct border. PC coverage was compared between the ECs within high Angpt2 expression zone (A2^hi) and low Angpt2 expression zone (A2^lo). n = 4, each group. Scale bars: 100 μm. *P < 0.05 versus A2^lo zone, Mann-Whitney U test. (H and I) Images and comparisons of NG2⁺ PC coverage onto ECs at the border zone. n = 5–6, each group. Scale bars: 50 μm. *P < 0.025, Kruskal-Wallis test followed by Mann-Whitney U test for post hoc pairwise comparisons (WT versus sham and WT versus Angpt2^iΔEC). (J and K) Temporal changes of relative expression of Tie1 in the ECs of infarct border. n = 5–6, each time point. Scale bars: 50 μm. *P < 0.05 versus sham, Mann-Whitney U test. Error bars represent mean ± SD.