Capillary densities at the peri-infarcted border zone in each group. A) More capillary densities were detected in the hypoxia-inducible factor-1α (HIF-1α) + mesenchymal stem cells (MSCs) group than other groups. (I) HIF-1α + MSCs group, (II) HIF-1α group, (III) HIF-1α-MSCs group, (IV) MSCs group, (V) Control group. B) The number of CD-31-stained capillary was expressed as the number/mm2. &P <0.05 vs. HIF-1α group, ☆P <0.01 vs. HIF-1α-MSCs group, △P <0.01 vs. MSCs group, * P <0.01 vs. Control group, ▲P <0.05 vs. MSCs group.