Figure 8

Resident macrophages Mac 2 express hmox1a for heme clearance during cardiac repair.

Reduced hmox1a-expressing macrophages were associated with heme accumulation under resident macrophage-deficient condition. (A) The bar plot indicates the hmox1a enrichments (–log₁₀ adjusted p-value) across macrophage clusters. (B) Expression of hmox1a was detected by in situ hybridization in the regenerative (–8d_PBS) and macrophage-deficient (–8d_CL) hearts at 7 days post cryoinjury (dpci). The dotted lines delineate injury areas; scale bars, 50 μm (upper panels) and 10 μm (lower panels). (C) Hmox1-expressing macrophages (arrows) were examined by immunostaining in the regenerative hearts (–8d_PBS) or resident macrophage-deficient hearts (–8d_CL) at 7 dpci. Quantification of the percentage of Hmox1⁺/mpeg1:mCherry⁺ macrophages and the number of total mpeg1:mCherry⁺ macrophages in injured area are shown in lower panels (left, Hmox1⁺/mpeg1:mCherry⁺ macrophages, n ≥ 5; p<0.0001; right, total mpeg1:mCherry⁺ macrophages, n ≥ 5; p=0.72). White dotted lines delineate injury areas; scale bars, 100 μm (left panels) and 10 μm (right panels). (D) O-dianisidine staining of regenerative hearts (–8d_PBS) and resident macrophage-deficient hearts (–8d_CL) at 7 dpci. The dotted lines delineate injury areas; scale bars, 100 μm. Quantification of staining density by ImageJ is shown in the right panel (n ≥ 7; p=0.0155). The heart samples under regenerative (–8d_PBS) or resident macrophage-deficient (–8d_CL) conditions are indicated by purple or green, respectively. Student’s t-test was used to assess all the comparisons by Prism 9.

Figure 8—source data 1.