Figure 4. rIL-13 signaling to CMs promotes CM cell cycle activity but does not mediate functional recovery after MI in adult mice.

(A) Experiment protocol. Group colors in the inset are used throughout entire figure. (B) Quantification of IL-4Rα mRNA expression from adult mouse whole LV tissue. (C) Survival curve up to 28 dpi after MI. (D) Quantification of fractional shortening (%FS) at 3 and 28 dpi. (E and F) Quantification of scar area as absolute mm² and scar length in 28 dpi hearts. (G) Quantification of CM cross-sectional area at the BZ. (H) Quantification of HW/BW ratios at 28 dpi. (I) Representative images of CD31, WGA, and DAPI staining of 28 dpi cardiac tissue sections. White box inset indicates zoomed-in region. Scale bar: 50 μm. (J) Capillary density at the BZ from 28 dpi cardiac tissue sections. (K) Representative images of EdU, cardiac troponin T (cTnnt), and DAPI staining of cardiac sections at 28 dpi. Scale bar: 50 μm. (L and M) Quantification of EdU⁺ CMs (cTnnt⁺) at the BZ and RZ. Data are shown as mean ± SD. Each data point represents 1 mouse. *P < 0.05, **P < 0.01, ***P < 0.001. Data compared by 2-tailed, unpaired t test in B, by Mantel-Cox in C, and by 2-way ANOVA and Sidak’s post hoc comparison in D. Interaction effect between treatment and genotype by 2-way ANOVA and Sidak’s post hoc comparison between PBS versus rIL-13 treatment for control mice and between Control versus IL-4Rα^CM-KO mice treated with rIL-13 in L.