Fig. 7: P-MSN/miR199a-5p reduces infarct size and cell death after myocardial infarction and improves myocardial contractile function.

a Experimental design. b Rats underwent with or without MI injury and received cy5-labeled MSN/miR199a-5p or P-MSN/miR199a-5p treatment through tail intravenous injection. Fluorescence signals were detected within 48 hours after injection, n = 3 rats. c Expression of dTyr-tub, MARK4, NOX4, and AGTR1 proteins in cardiac tissues 7 days after infarction were detected by immunoblotting, n = 3 rats. d The sections of hearts from the sham-operated group and 7 days after myocardial infarction in NC or miR199a-5p mimic-treated rats were labeled with Tunel staining (red) and immunolabeled with ɑ-actinin (green) and nuclei (blue), n = 3 rats. Bar=25μm. e Comparison of representative contraction traces in the sham group, the MI group, the P-MSN/NC + MI group, the MSN/miR199a-5p+MI group, and the P-MSN/miR199a-5p+MI group for 5 seconds. Statistical analysis of maximum strain in different groups of injured hearts, n = 5 rats. f The echocardiographic images of 1 week (above) and 4 weeks(bottom) post-MI injury in the sham group (control group), the MI group, P-MSN/NC + MI, MSN/miR199a-5p+MI and P-MSN/miR199a-5p+MI group. Representative parameters of left ventricular function based on echocardiography of each group at 4 weeks after MI injury, n = 6 rats. g Mason’s staining displayed the fibrous tissue (blue) and myocardium (red) of sections of hearts from rats in different groups. Scale bars: 1 mm. Statistical analysis of infarct size of the infarcted heart in different groups, n = 6 rats. Data for (b)–(g) are presented as mean ± SD. The p value for (b)–(g) were generated by one‐way analysis of variance (ANOVA), followed by Tukey’s multiple‐comparison post hoc test. *P < 0.05, **P < 0.01, NS, not significant. Source data are provided as a Source Data file.