Fig. 5: LncBAR promotes adult cardiomyocyte proliferation and heart repair post-MI.

a Schematic of the experiment design for evaluating the role of LncBAR in adult mice post-MI. Adeno-associated virus serotype 9 (AAV9) with LncBAR overexpression driven by cardiac specific promoter cTnT (AAV9-cTnT-LncBAR) or control virus (AAV9-cTnT-Control) were intramyocardially injected into the injured site immediately following MI. Echocardiographic assessments were performed weekly. Heart samples were collected 2 weeks or 6 weeks post-MI. b Quantification of total cardiomyocyte number from hearts 2 weeks post-MI following LncBAR or control virus treatment (n = 5 mice). Hearts were perfused using a Langendorff apparatus, and isolated cardiomyocytes were counted using a hemocytometer. c Quantification of mononucleated, binucleated, and multinucleated cardiomyocytes isolated from hearts 2 weeks post-MI following LncBAR or control virus treatment. Hearts were perfused using a Langendorff apparatus, and isolated cardiomyocytes were stained with α-actinin and DAPI for identification and nuclear counting. (n = 5 mice). Scale bars, 20 µm. Representative confocal z-stack images and quantification of Aurora B+ cTnI+ CMs (d) Ki67+ cTnI+ CMs (e), and pH3+ cTnI+ CMs (f) in the border zones of mouse hearts 2 weeks post-MI. Yellow arrows indicate proliferating CMs (n = 12 fields, 3 mice/group). Scale bars, 20 µm. Representative Masson’s trichrome staining (g) of heart cross-sections and fibrotic area quantification (h) 6 weeks post-MI (n = 5 mice). Scale bars, 1 mm. Echocardiography analysis of mouse hearts. LVEF (i): left ventricular ejection fraction; LVFS (j): left ventricular fractional shortening (n = 4 mice for sham groups, n = 8 mice for MI groups, but 2 weeks post-MI n = 5 mice for MI groups). Data are presented as mean ± SEM. Statistical significance was determined by two-tailed unpaired t test or two-way ANOVA with Tukey’s multiple comparisons test. *P < 0.05, **P < 0.01, ***P < 0.001.