Characterization of the Cardiac Structure and Function of Conscious D2.B10-Dmdmdx/J (D2-mdx) mice from 16–17 to 24–25 Weeks of Age

Figure 1. BW evolution in mice from 16–17 to 24–25 weeks of age. Data are the mean ± SEM, n = 10 for each group. Mixed-effects model; p < 0.0001; Šídák’s multiple comparisons post-hoc test; **** p < 0.0001 vs. DBA/2J WT.

Figure 2. Epicardial fibrocalcinosis of the right and left ventricles in 16–17-week-old mice. Representative digitalized images of the anterior and posterior sides of formalin-fixed DBA/2J WT and D2-mdx mouse hearts, acquired by a high-resolution scanner in 16–17-week-old mice. Right ventricle (RV); left ventricle (LV). Scale bar = 1 mm.

Figure 3. Heart rate, left ventricular echocardiographic variables, and pulmonary vascular resistance parameters evaluated in 16–17-week-old mice. Data are the mean ± SEM, n = 20 for each group. (A) Heart rate (HR); (B) left ventricular ejection fraction (LVEF); (C) cardiac output (CO); (D) stroke volume (SV); (E) mitral E inflow velocity (E vel); (F) pulmonary artery acceleration time (PAAT); (G) PAAT on pulmonary artery ejection time (ET) index (PAAT/ET). * p < 0.05, ** p < 0.01, and **** p < 0.0001 vs. DBA/2J WT mice, unpaired t-test.

Figure 4. Heart rate, left ventricular echocardiographic variables, and pulmonary vascular resistance parameters evaluated in 8 weeks of follow-up (from 16–17- to 24–25-week-old mice). Data are the mean ± SEM, n = 10 for each group. Two-way ANOVA or mixed-effects model. (A) Heart rate (HR); (B) left ventricular ejection fraction (LVEF); (C) mitral E inflow velocity (E vel); (D) mitral A inflow velocity (A vel); (E) left ventricular cardiac output (CO); (F) left ventricular stroke volume (SV); (G) pulmonary artery acceleration time (PAAT); (H) PAAT on pulmonary artery ejection time index (PAAT/ET). Šídák’s multiple comparisons post-hoc test; ** p < 0.01, *** p < 0.001, and **** p < 0.0001 vs. DBA/2J WT.

Figure 5. Right ventricle weight + left ventricle weight normalized by BW in 16–17- and 24–25-week-old mice. Data are the mean ± SEM, n = 10 for each group. Right ventricle weight (RVW); left ventricle weight (LVW). ** p < 0.01 vs. 16–17-week-old DBA/2J WT mice, unpaired t-test.

Figure 6. Extension and thickness of epicardial fibrocalcinosis areas (crusts) in the 16–17-week-old D2-mdx mice. (A) Angular delimitation of the left ventricle (LV; light blue line) and right ventricle (RV; green line) (1); example of LV and RV fibrocalcinosis angular extension in the D2-mdx mouse, with each angle delimited by pink segmented lines (2); example of LV and RV fibrocalcinosis thickness yellow lines) in the D2-mdx mouse (3). Data are the mean ± SEM, n = 10 for each group. (B,C) RV and LV epicardial fibrocalcinosis extensions, respectively; (D,E) RV and LV epicardial fibrocalcinosis thicknesses, respectively. ** p < 0.01 and **** p < 0.0001 vs. DBA/2J WT, Mann–Whitney test.

Figure 7. Fibrosis percentage in the right and left ventricular wall and interventricular septum in 16–17- and 24–25-week-old mice. (A) Fibrosis distribution in the hearts of the 16–17- and 24–25-week-old D2-mdx mice. Sections were stained by Sirius Red 0.1%, magnification 200×, scale bars = 500 µm. (B) LV epicardial plus interstitial fibrosis; (C) LV epicardial fibrosis; (D) LV interstitial fibrosis; (E) IVS fibrosis; (F) RV epicardial plus interstitial fibrosis; (G) RV epicardial fibrosis; (H) RV interstitial fibrosis. Data from Sirius Red staining analysis. Data are the mean ± SEM, n = 10 for each group. Left ventricle (LV); intraventricular septum (IVS); right ventricle (RV). ** p < 0.01, *** p < 0.001 and **** p < 0.0001 vs. 16–17-week-old DBA/2J WT mice. °° p < 0.01, °°° p < 0.001, and °°°° p < 0.0001 vs. 24–25-week-old DBA/2J WT mice, Mann–Whitney test.

Figure 8. Plasma concentration of cardiac biomarkers in the 16–17- and at 24–25-week-old mice. Data expressed as the median [Q1–Q3], n = 10 for each group. (A) High-sensitivity cardiac troponin T (Hs-cTnT); (B) N-terminal pro-atrial natriuretic peptide (NT-proANP). Segmented line indicates cutoff for normality values. * p < 0.05 vs. 16–17-week-old DBA/2J WT mice; ° p < 0.05 vs. 24–25-week-old DBA/2J WT mice, Mann–Whitney test.

Figure 9. Fibrosis deposition in the diaphragm muscle in 24–25-week-old mice. Data are the mean ± SEM, n = 5 for each group. Diaphragm (DIA). °° p < 0.01 vs. the DBA/2J WT mice, Mann–Whitney test.

Figure 10. Study flow-chart. BW, body weight.